Just gonna throw my opinions around on some issues, if anyone wants to take a listen:
Quickplay needs to be changed - As for a short-term change, Valve needs to enable community servers by default in the quickplay search. They were talking about this many months ago on HLDS relating to the abuse of the Quickplay system, but nothing has been solved (or appears to have been changed) in regards to getting community servers back on by default.
Next problem: There is no incentive for quickplay server owners to run custom maps. A custom map on your rotation effectively shuts off traffic for the duration the map is on the server. This basically means, you have to rely on the people who were on the previous map, or people coming in from the server browser. You see that big giant "Play Multiplayer" button on the main menu? That's what most casual and new players use.
Custom maps need some way to be incorporated within Quickplay, or I figure custom maps servers will continue to die as they have been since early 2012/late 2011. Yes, there are many custom maps servers still around, but are mostly gimmick/custom gamemode servers that don't need Quickplay in the first place. Many serious custom maps are long forgotten unless the competitive community picks them up.
Instead of banning all custom maps outright, I suggest a possible filter for map prefixes, restricting gamemodes to what TF2 already has. Of course, this does not benefit people who create custom gamemodes, and could probably be circumvented with a map recompile, but I figure it's better than nothing at least. Ideally, this would filter out things like vsh_ or trade_ from Quickplay but keep custom pl_ or cp_
About the map workshop - I think it's a great idea, and I've actually emailed Valve in the past about it. I hope TF2 gets it as soon as possible. What many TF2 maps need is the publicity of the Steam Workshop, for other people to see, and also for Valve to see. Of course, the feedback is awful, but I don't think anyone takes that seriously, not even the hat-makers. People use Facepunch/TF2maps.net/other sites for serious feedback.
Preferably, I'd like the map workshop to work how the item workshop does, where you are submitting something to be approved by Valve and added into the official game. It sounds simpler to implement a curating system (already in the game) for maps than to overhaul for a subscription system/pay 2 play system CS:GO has.
Paying the map-makers - We're going to need some way to pay the map-makers without doing CS:GO style operations, which is a decent challenge to overcome. The best way about it would to probably involve trading and the TF2 economy. You can keep doing it the Valve way, with aesthetic incentives to give money, or you could do something passive like marking crates and such. There's probably many ways you could go about it.
Finally, have some maps I think should be considered for use in the game (based on pure nostalgia):
- pl_5curve
- pl_borax
- pl_boundary
- pl_cashworks
- pl_deadwood
- pl_halfacre (replace pl_hoodoo with this? :thumbup1

- pl_outback
- pl_repository
- pl_stovepipe
- pl_swiftwater