RNG swing is a bit too much of a factor. Especially since certain items like zombie dog and even certain deities a useless to the point players are better off not unlocking them if they want a certain strategy.
I concur; while I love the spontaneity of DD, we currently have the preparation system and the RNG pulling in two separate directions. The prep system encourages players to enter a dungeon with a plan in mind and to optimize their load-out with respect to this, while the RNG forbids such an approach and forces players to be very flexible with regards to sub-optimal in-dungeon assets.
This has lead to "selective unlocking" strategies that currently are the hot thing. I'm personally running a Mystera/Jehora deity combo, and am looking to complete my trio with Pactmaker, though I'm being a little sloppy with item unlocks and am more or less allowing my shops to become cluttered. I don't know what the answer is, but I hope Desktop Dungeons can find the happy medium between these two factors.
it currently feels like there are WAY too few spaces, making it a bit too restrictive.
As it stands currently, Trisword, Burning Heart, Stone Heart, Crystal Ball, Dragonshield, Sensation Stone and Avatar's Symbol are pretty well mandatory for specific high-end strategies... oh wait, that's 7 out of 6 of your locker slots, hmmm....
I've long held that we need more slots, because locker scumming just isn't fun. Unfortunately, the only real solution as it stands right now is to make and maintain two different accounts with different locker load-outs.
I have an idea: have a bigger locker, but items that are currently in your locker never appear in shops (unless and until the item is removed from the locker). That makes for an interesting choice: you want to have cool items in your locker so you can prep them, but you also want to leave cool items out of your locker so you can buy them;
I strongly disagree with this. This means your favourite items
will never appear. This also greatly discourages lockering two complementary items, such as both the Fire Heart and the Crystal Ball.