But then you are making them JUST halflings and JUST Gnomes etc.
Not if they're actually written well.
Take the defining
kender trait of stealing everything in sight. First off, why? Mostly for comedy reasons, because they're so "innocent" that they don't know that they're doing bad things--but honestly, that's neither funny nor a show of innocence (especially since they lie about stealing). Give them a legitimate
reason for stealing stuff. Say that they have a philosophy--or even a non-theistic religious belief--that says it's OK to have personal property, but it's always wrong to hold on to it selfishly if someone else needs or wants the thing. Say that kender either don't care that other cultures think differently or that kender actively believe that other cultures are
wrong when they hold onto things.
So what this means is that you will have kender who accept this philosophy blindly and "handle" things whenever they want to; those who accept the philosophy but also realize that they shouldn't inflict their beliefs on other people; those who reject the philosophy; and those who come up with variants on that philosophy. More importantly, this prevents the kender from being a one-note annoyance because it is literally a choice as to how the player wants to deal with the handling, not just how much of a jerk the player wants to be.
This is just one way to "handle" kender (hur hur) without turning them into "just halflings."
Heck, you could leave kender as-is if everyone else
realized they were a punch of pack-rats and treated them as such, instead of having the books insist that humans think they're adorable.
Take the
gnome trait of building overly complicated things that don't work right and shunning anyone who actually makes something that works well. Realistically, this was for two purposes: to make them a "funny" race, and to keep their inventions from actually making radical technological changes to Krynn.
Again, lots of ways to do this without making them a comedy race.
Let them build technological wonders. But say that they
don't share technology with outsiders except in very rare cases, and stealing a bit of gnome tech means they'll send an army to retrieve it (or assassins). Or say that they've skipped clockwork and steam and gone right to internal combustion, but nobody else has the materials (including oil) necessary to build such an engine (heck, you could also go with steam and just say nobody else has been able to make a boiler that doesn't leak or explode) or is willing to pay to build such engines. Or borrow a page from Eberron and Sharn and say that the tech only works around Mount Nevermind but not outside of it, due to the magical nature of the place.