That doesn't imply passive role in combat. You can make this formula work without forcing mage to nose-picking...
You can make anything work.
But that doesn't make the earlier, established formula somehow shit.
Think in terms of a typical strategy game. You can rush to make some basic units/ships and attack the unprepared enemies (zerg rushes in Starcraft). Or you can wait it out, properly upgrade and develop your army and then do the attacks. Just because the later strategy has to wait for a while to see some proper action, that doesn't mean we should necessarily insert some token crap for them to do to make things exciting.
The way I see it, you can either give him a useless, generic energy blast, which is just a sling shot with nice visual effects. Or you can make that energy blast highly effective, or make him a decent at melee/range combat, in which case you just overpowered the shit out of him and everyone will roll wizard next time. There's a fine middle ground to make it work, sure, and I respect Sawyer for actually trying to improve the way character development works. But it's a pretty heavy risk.
I'm going to keep emphasizing this: one of the biggest motives why I like old-school games is because of
utilitarian reasons. It's a tested formula for most of the time, it's cost effective and resource effective and it's beloved. The visual are (theoretically) not as resource intensive as modern graphics, yet they look times better. The character development systems are more complex and better developed and they work really fine. The dialogue is written and doesn't have voice acting and contributes more to the atmosphere. By not pushing the technology and design forward, you can just focus on delivering good content. Even something as simple as the interface is better in older games because it shows more information in a more efficient way, for example. I'm not a nostalgiafag, my experience with cRPGs comes all from abandonware and trying old-school cRPGs after playing the modern shit in mid 2000s.
Mages not being constantly useful earlier in the game was not a giant problem. Infinitron remembering it sucking in
retrospect after Josh pointed out the problem doesn't really count. It's not like BG1 itself was really that exciting early game. Shit, it's not like fucking Fallout games themselves were exciting early on. But you know what, Fallout didn't give you some shitty energy pistol outside of the vault just so you can feel better about yourself for tagging that skill.