If you aren't running out of adjustment you don't need one. Not needing something but having it anyway isn't a big deal, but like most things there is pluses and minuses. Pluses are more elevation adjustment, some flexibility in mounting and scope interchange ability. Both are good if you need them and useless if you don't.
Minuses are obstructing the loading port, potential higher than optimum mounting, they cost sometime, and weigh something. I see rifles that are harder to load than they have to, with adjustable stocks that they wouldn't have needed otherwise, all at at cost in dollars, just to solve a problem they didn't even have.
I'm guilty to, having many rifles that have slanted rails that they don't need and will never need. Just a pain in the butt that I had to pay for.
