Barbarian Berserker Frenzy, there are other ways to get a bonus melee attack that do not?

@dmvarrowe69Berserker – why does Frenzy cause exhaustion when there are other ways to get a BA attack that do not? Seems out of place Frenzy's excellence rests in the fact that the bonus melee attack has no conditionals. Just keep that rage going!

— Jeremy Crawford (@JeremyECrawford) July 21, 2016