Except that they only did half the job, elves and rogues were never proficient in bastard swords before.
I'm right there with you on the rogues getting proficiency with longswords, it doesn't make much sense. Then again, straight rogues were never weapon monkeys so if it bothers you that much get rid of the proficiency since it's going to be rarely used anyway.
Elves? They're the munchkin race of 5E (I kid, mostly) so why wouldn't they get proficiency? I could see removing that one too and putting in a note about how they call their rapiers "elven thin blades" because they're snooty that way. But that's probably me just mostly being bitter because any time I run an elf PC it dies before it hits 3rd level.
End of the day I just don't see a big issue having to do with names of weapons that never had any hard historical definition anyway. I've also seen plenty of longswords being used by PCs, your experience may vary.
Want to discuss how to have more realistic bonuses from dexterity? I'm full of opinions. Well, everyone says I'm full of it anyway. But it affects more than just swords, it affects bows, AC, a few other things.