Why aren't you using seasonal maps anymore? Why was season 2 different than other seasons? I'd love to see winter and halloween maps again...
If you're gonna say "We don't have the resources to create seasonal maps." then you're wrong! There are many other people who does that for FREE! Please bring them back. 
Also check this video out (Inspired from it): https://www.youtube.com/watch?v=6ReOztCzyec
Friendly Ram1 votesI remember a riot post stating that they wanted to make them higher quality and with the new rift they couldn't reuse there older ones.
Kargaja1 votesOkay, good to see that they at least consider using them in future :).
ModWulf Helhammer1 votesThis one to be exact
VladTheMage1 votesAt least use some custom map skins some people created. They aren't low quality. I hope they don't do this due to bugs incurring rather than being afraid to give credit.
Serpents Embrace1 votesDidn't they update the map after doing the seasonal ones? From what I remember, they only updated the one because to do otherwise would literally triple the workload...
And with how poorly a lot of important parts of the game have been handled I don't think diverting resources to seasonal alternate maps would be a wise choice.