It's also worth remembering that the most successful Trek was in fact TNG.
Now how that may have been handled badly come movie time, and how that all ended up, balanced out with the 20 year head start TOS had (not to mention the fact that the two are intrinsicly the same thing) might be a different thing to think about..
But it is definitely TNG that had the most success in its time, and a comparable amount of success afterwards (novels continuing after its finish, never ending loops in syndication, conventions to this day....All comparable to TOS...Picard is also a popular cultural icon...) so pretending the only commercial interest is in TOS is inaccurate. The other Treks aren't able touch the big two, but there's a reason the baby gros , pizza cutters, dressing gowns and onesies still pour out in TNG themed stuff as well as TOS.