A more accurate comparison would be choosing to run a fighter who uses lighter weapons and light-medium armor, thereby choosing not to use at least one free feat of his own, namely heavy armor proficiency. Possibly 2 if he's a TWF build, eschewing the use of his freebie shield proficiency feat.
You gain something by using lighter weapons (a dex based fighter is viable through feats), especially a TWF build. You also gain something by choosing lighter armor, specifically the DEX bonus to AC. Since you are using light weapons and light armor, assuming you are not voluntarily hamstringing yourself and take proper feats, you now use AC both for hitting AND to better your AC (plus significant other benefits if you are a TWF). This is a tradeoff but it is not necessarily a sacrifice. You are giving up something to get something. Unless, again, you for some reason choose to not take the proper feats and are voluntarily hamstringing yourself - but this is a choice.
Since the scribe scroll feat is free, the xp cost is negligible and the gp cost almost so(literaly for low level spells it is a few experience points and under 100 gold which at mid to high levels is barely within bookkeeping guidelines) the mage gives up nothing but versatility and effectiveness (so yes it is more akin to a fighter voluntarily sacrificing to-hit).
The main point, that the 3e wizard can easily and with little effort or sacrifice step on the toes of other classes (while they cannot do so to him without great effort and expense) is IMO a bug not a feature.
That you choose not to do so does not mean it is not a bug.