Well, it helps a lot that Lua is by design a very small language :)
Python is actually much bigger nowadays -- I would challenge someone to come up with something this simple that doesn't leave out a lot of stuff you will encounter in real code.
The extra features ("bloat") do matter. I like the idea of Lua a lot, but when I started programming in it, it unfortunately felt like a less capable Python to me.
Lua and Javascript are quite similar in that way: nice little languages that fall apart really quickly when you try building anything reasonably large or complex.
I don't really understand the attraction, except in certain niches like Lua as an embedded scripting engine, when you really need something that can be trivially sandboxed.
