However, as I started thinking about how I might tweak and houserule the class, it occurred to me that the problem might have less to do with the class itself (which probably doesn't actually need tweaking or houseruling at all) than it does with the way I personally have been designing adventures.
My adventure set-up in general tends to follow Moldvay's proportions (in or out of dungeons), even when I don't do it randomly:
These proportions really equate, in many ways, to the class-focus of a given room / outdoor scene / encounter / whatever. Fighting monsters is where the fighters and clerics excel, especially at low levels. They have the best armor (fighters and clerics), the best weapons (fighters), the ability to turn undead (clerics), to heal post-combat (clerics), etc. Similarly, each "trap" result give the thieves their moment in the spotlight.
This made me realize that one area where I think I've been deficient is in providing magic-users their time to step up front and center. I suspect this is largely because of the fact that a) the above table has informed my thinking quite deeply since I was twelve, and b) within that framework, I've used "specials" in a very broad, general sense, including "special monsters" (again for the fighters and clerics) or "special traps" (again for the thieves) or even just "weird" stuff, not directed at any particular class.
From this it seems that magic-users may be getting short shrift in my games.
What I'm tempted to adopt in the future is an approach where I think of "specials" as specifically arcane, or else based in lore, language and book-learning; something where familiarity with magic or other study-based knowledge would be of substantive benefit to the party in dealing with some obstacle (though not necessarily required), aiming to give the magic-user something to do on a fairly regular basis, the same way that the "trap" result does for the thief, or the "monster" result tends to do for fighters and clerics.
To remind myself, I'm going to rewrite the stocking table I use like this:
This won't involve re-tooling the class itself at all, but my actual dungeon / adventure keys will have notes in the entries for any "specials" stating things like "any M-U will recognize this device and realize X about it" or "any M-U has a 4 in 6 chance to understand the markings; others have a 1 in 6 chance" or "the lever will only respond to the touch of an arcane spellcaster," and so forth. This will give the player with the magic-user a bit more of a role, and give a party a real reason to want to have one, even in (or perhaps even especially in) first-level play.