Pretty sure I did the majority of my runs Purist during my initial playthrough because I had to save money for bank upgrades and class building upgrades. So put me in with the "locker space didn't effect me" crowd.
That said, after I unlocked the important things locker space started to be an issue. Rather, relockering things became annoying so I basically stopped doing it unless I really needed a certain item (for testing bugs and such, like the Orb of Zot on CO issue).
Nowadays, what keeps me playing is... I don't even know. I have every item, class, dungeon and building unlocked and the only things I can do now is grind for ridiculously expensive bank upgrades and a 100,000 gold locker slot. What I think the game might be in need of is some actual completion rewards, because it feels like "completion for the sake of completion" at this point, and the Alpha had tangible and useful rewards for completion which was a much better situation IMO.
EDIT: because I forgot to mention that certain balance issues are still bothering me. When I can finish Slime Pits with an Elf Monk after getting a bad roll on the "LEMMISI?" glyph and revealing the entire map at level 4, simply because I had enough knowledge to prep an extremely broken item (Trisword) and then last-minute worship GG for 2 hits of Cleansing, I have to wonder WTF the devs are doing because balance can't possibly be in a good place when that's doable.