Lack of vision is certainly a problem. They waited until every single carrier has maxed out their gates to get started on a concourse expansion that literally will be 100% full the day it opens. If you call that forward thinking I do not know what to tell you.
The bathrooms have been a disgusting, overcrowded mess for YEARS. This isn't a new issue. The elevators and escalators have been unreliable for YEARS. Also not a new issue. The traffic on Pena is getting worse every day, and instead of widening the part that is actually congested (I-70 to E-470) they are widening the already widened part and putting the main section as last. Major fail in planning. Again, they will wait until the problem is a crisis before doing anything about it. That is the way this airport reacts to everything - reactionary and not proactive.
I think one of the biggest issues is that the airport has tried to keep it's cost low and I think this is part of the reason as to why there has been so much growth in recent years. DEN has the lowest CPE of any UA hub, from $15 less than Newark to $.50 less than IAH. Even after the expansions/ renovations currently happening the airport still expects to be the cheapest of the UA hubs, this also helps play into why DEN has always been so profitable for UA. When you look at the history of the airport it took them 15+ years to pay off the initial debt and get down the CPE. When WN wanted more gates they got them fairly quickly allowing them to continue growing. When the A-Line started construction the airport had agreements with RTD to build the station so they had to start construction on that to have everything completed by 2016. Since then the hotel has been preforming better than expected in terms of revenue generation. Once the hotel was complete the airport started planning for more gates/ great hall expansion as the airport was growing quickly hitting 58 million pax. The original plan was to add 24 gates across the three concourses but after talking to the airlines that number was increased to the 39 that are being worked on today. As the airport was nearing 25 years old all conveyances and restrooms were included in the plan in addition to replacing/adding train cars. While the airport could have moved up the timeline on these projects the amount of bonds that would have been issued would have increased the CPE much quicker than the airport would have liked. One big thing to keep in mind is that UA and WN have a lot of say in these projects and the timing of them as they foot a large portion of the bill.
In the mid 2010's the airport started studying Pena expansion as it was becoming more congested quicker than originally expected due to the amount of development that occurred in Green Valley Ranch and Reunion areas. Pena has now hit the point where the first sections after I-70 now have more non-airport traffic than airport traffic. This has lead to some conversations with the FAA about how Pena should be expanded as the FAA does not want airport funds to be the only funding source for any Pena improvements West of E470 , the FAA wants the surrounding cities to assist with the funding, which I don't disagree with as non-airport traffic is growing faster than airport traffic. When the new Tower on ramp was built it took an agreement with Commerce City, the City of Denver, and E470 as the airport was never allowed to fund it as it would not contribute to the airport in any way, in the agreement Commerce City even pays the airport for the maintenance. Pena was always split into 4 phases with the area from Jackson Gap to the terminal being the first phase, the second phase is from I-70 to 56th. The reason that the Terminal phase is first is because the improvements are less about Pena and more about Jackson Gap and improving the Ground Transportation situation with Uber and Lyft growing as much as they are. Pena does get one additional lane in each direction, but Jackson Gap gets completely rebuilt with a new Pena interchange and a new intersection at 75th as the intersection is a disaster. Uber and Lyft will be relocated from the Mt. Elbert lot to the new holding lot just off Pena which should reduce passenger wait time as it often takes 15+ mins for their ride to reach the terminal from the Mt. Elbert lot. To add to the complications the city has told the airport that instead of expanding Pena they should find ways to reduce vehicle trips to help the environment. When the first phase of Pena was approved the airport was told that they needed a better plan in place before any future expansions would be approved.
The LED welcome sign while it has been a mess due to technical issues, I don't think it was the worst idea. The old color changing sign needed to be replaced as the specialty light bulbs that it required were no longer being manufactured and had to be special ordered costing 100,000+ each. That was the main motivation for the new sign and they had a solid plan in the beginning, the biggest screw up with the sign was the airport not doing all of their homework about the rules about highways leading to airports. Even with that mess up, the advertising on the sign is expected to pay the sign off within 10-15 years which was why the airport insisted on having such large digital displays, while the airport could have spent 10-20% on a smaller color changing sign, it would probably not have the same advertising capabilities that the current sign has. All of the current work on the sign has been under the signs warranty.
While I don't agree with every decision the airport has made over the past 5 or so years, I understand the reasoning for a lot of the decisions. In day to day operations the airport generally runs fairly smoothly for the amount of traffic that passes through the airport, especially when you compare it to other airports that handle similar amounts of traffic such as JFK or SFO, and I think that the airport is heading in a good direction for the future and I would imagine at least UA and WN agree.
Chart from the airport showing CPE per major hub airport: