If there were no tinkering cap.. every character with a few thousand plat
lying around (40th plus folks in general), regardless
of race, class, etc. can roll up a 1st level gnome (or if we leave limit
at 16th level, then power level a small gnome necro to 16) and get them
maxed on tinkering in a few days. This would crush our market. If you
had a 50th hi-elf enchanter, there's no way you'd feel like starting a new
gnome mage and take him to 40th JUST to tinker (it may have a factor in their
choice if they're choosing a new character anyway).

I'm 35th level, been tinkering since 29th. This is my first character and
I dont have lots of cash (mostly thanks to tinkering). If the cap is removed
I'm confident the market will crash worse than it already is.

Jewelry works this way too.. any first level character can get 200 skill BUT its a continual hassle to get enchanted gold/plat if yer not a high lev
enchanter.

I am certainly bias, because my meager savings only lets me advance in spurts.
If 50 master tinkerers show up on my server I'm probably screwed. All my
previous time and cash (ALL that cash!) will be wasted. If they
were all 16th level, I must admit I'd probably be a bit annoyed.