My current game where I play a wizard (started at level 3, now level 7) had no real dungeons so far. And there was never a chance to block enemies from coming at you because the spaces were all wider or allowed for multiple ways.FWIW, I think a proposed change to casters should come along with some additional redesigns to other systems. Sticky front lines should be one of them.
Low-level play in TSR era was built with certain assumptions. In particular dungeons with lots of 10' corridors (you could stick a row or two of 3-abreast front-liners between the enemies and the squishies). There also were (depending on specific game) rules about once you hit melee, you could either stay and fight, flee, or retreat, but not work your way around your opponent and rush their rear line. If you could somehow situate yourself to 'flee' from melee into an enemy rear-line (fleeing so you would get in an attack), IIRC each front liner would get their full attack iteration on you. Obviously everyone didn't play like that, but I also remember that as party sizes shrank (from scads of hirelings) and as we left the narrow corridors, we all did institute some kinds of house rules to address this because otherwise outdoor encounters were murder on the magic users and thieves that enemies could just run up to.
Regardless, my point is of course you can still use those tactics now (minus worse sticky front-line rules), but then you are choosing to stick more to the dungeon structure of old. My impression is that that is a non-starter for a lot of play groups.