I have no problem with them because they help stretch out the map, and give great scenery to the game.
I do wish some of them had more trees though. We never really got the "Tall Trees (RDR)"-style forest that I was hoping for, and yes there could have been cabins or other interesting things to explore, but we've gotta remember that there were limitations.
I'm sure when R* first thought up the idea of multiple mountains and peaks they had all sorts of ideas, which all had to be taken off the table at some point or another to keep the game running smoothly.
I'd rather had a smaller denser, more detailed map than a map that's too big for current generation consoles to handle.
Thats great and all, but thats suggesting that those were their options, but they weren't.
Taking away three mountains wouldn't have added much detail to a remaining mountain if any detail at all, because it wouldn't have made it any more possible for more trees or details to occur in any given spot at one time. With those mountains, they gave us extra land that they didn't have to add, but chose to, and I thank them for it.