I really hate this.
we need to return to 3.5e differentiation of
1. Spells
2. Spell-like ability
3. Supernatural ability
4. Extraordinary ability
This alone would not address the issue. I mean, it might
help, but keep in mind that half of those things are still spells anyway, either directly or indirectly. So we would have just ended up with half these "spells" instead being "spell-like abilities", which are just spells with more steps.
For me, I think we just need to have a design which understands that bespoke abilities are not bad in and of themselves. That doesn't mean we should let them proliferate without use. We shouldn't. They should be for a purpose. But the way the 5e design team treats them, you'd think they actively wanted to make EVERYTHING a literal actual spell, even things that
aren't even magical at all, get turned into spells. I just...I don't get it.
Doubly so when "everyone is a spellcaster" has been a major, major complaint about game design in the past.
But, more importantly, the way you make species design better is not (strictly speaking) by enforcing the above categories. It's by making it so that each species has
active abilities that make them distinct. Consider that elves have had the whole "trance instead of sleep" thing for ages, but it
never comes up as the thing folks love about elves. That's a really really big clue! Passive abilities have their place, and shouldn't be totally excised any more than bespoke abilities should. But passive abilities aren't what makes something cool, fun, or memorable. Active abilities are what do that.
"High Elves" (I still prefer the term "Eladrin") have a teleport. Dragonborn have a breath attack. Tieflings have Hellish Rebuke (which should not be a spell, sorry Warlocks, it just shouldn't). Orcs have their blood rage. Etc. Tap into
that sort of stuff, and you'll have people beating a path to your door. Because you've made it so that each species
feels different to play, because they actually DO different things, rather than merely having slightly different numbers.