Once you learn the fn layer on a 60% it's just as fast as a TKL. Let's be real, people don't complain about symbols being hidden under number row and you wouldn't want them on an extra row of dedicated keys.
If you need a number pad then that it's a totally legitimate criticism. But you can always add a stand alone number pad. And that it's still more ergonomic.
60% is love, 60% is life
The biggest difference between 60% and TKL in my use case is the arrows and edit keys. Having ingrained in my muscle memory from many years of coding exactly where the arrows are and how I use them in combination with Shift, Home and End to edit text really fast is so hard to adjust to on a 60% with a Fn layer.
There has not yet been a 60% Fn layer design that I've seen that I would be able to use as fast as the dedicated ones on a TKL and that makes a big difference when most of the day you're editing code. The KBT Pure has a great Fn layer layout and I'm used to it enough to function in my daily work with it, but it's still nowhere near the speed I can get on a TKL, unfortunately.
Still, I use the Pure at work since the other benefits of 60% outweigh the speed hit.
IMHO, gaming on a 60% is great, since it forces you to rather bind keys closer to your finger home position, sometimes in combination with a modifier and I have found that to be faster than using F keys (once you get used to the bindings).