We've had this discussion. While it's quite easy to believe that Starfleet would have [and shown in DS9's period WAS SHOWN TO HAVE] a large percentage of cruisers, there is no arguing the usefulness of the smaller ship design. I lump all policing, patrol and such craft under the term 'escort'. They're a small vessel that can be everywhere because they're cheap, respond to most any problem, and if they can't fix the situation, they can radio in bigger help. If they don't survive, then you've lost little in terms of personnel and materiel.
I still hold by my 60/40 split for the Rogverse, and might even argue for a 50/50 split by TNG's time. If I included such craft as the really small craft, runabouts and little defense ships... might even skew that more towards escorts by 10-20%.
--thu guv!