You have to look at the purpose of why they make hammerless revolvers. It's to eliminate/reduce the possibility of snagging the hammer when drawing from pocket or other place of deep concealment. While it can be done not too many people carry a 4" N frame IWB everyday as their main carry gun. Just not the market demand.
It use to be common with guys carrying N and K frame guns when wearing suit jackets to bob the hammer. The hammers would eat the heck out of jacket linings.
Yep, that's how it runs. My "E" frame 632 Centennial currently rides in my shoulder holster and needs no snap to hold it in place.
If I'm taking out the garbage and don't want to throw on my holster, I can slip the J frame .32 Magnum into my back pocket and take out the garbage, not giving it a second thought. It's quite convenient.
I cut the hammer spurs off all my large frame revolvers except my .44 Mountain Gun. The only reason the .44 still has one is because I've considered selling it and would like to keep it intact. I don't own any revolvers with a barrel longer than 4" and I consider them all concealed carry guns first and everything else second. And I believe a hammer spur has no place on a concealed carry revolver, N Frames included.
All said and done, I think a 625 Centennial would be kind of cool.