Okay, so I've always hated the "Vancian" magic rules in D&D with the miserable spell-slot system. I consider it the worst part of the game and yet except for 4E it was one of the few sections of the rules which remained almost unchanged from edition to edition. I found early on that as a wizard/magic-user you ran out of spells quickly and then had to resort to your crossbow (or darts!). Naturally, your ranged weapon attack bonuses sucked and so you were a pretty crappy crossbowman at that. At lower levels you ran out of spells so frequently that, in effect, you were actually a crappy crossbowman who also knew how to cast a couple spells.
I call this Crappy Crossbowman Syndrome.
When I started reading about the 4th Edition rules I was thrilled. Finally, you could be a spell caster who, um, casts spells all day. Finally, they had driven a stake through the slimy, pustulant heart of the "Vancian" magic system and cured Crappy Crossbowman Syndrome! My greatest hope for D&D 5th Edition was that they would retain the 4th edition magic system, albeit likely with some modifications. But no, they went right back to the traditional Crappy Crossbowman Syndrome approach.