Why do you want any rifle? Because you do. One grabs you and you're hooked on it. Same with the M1A. For me, it's a great fun rifle for steel plates as 400yds with NM sights and my handloads. It's the first peep sighted rifle I ever shot. Got my hands on a M14 back in Basic Training a long time ago and by the time I was done I could do pretty well even out to 600 meters with it back then.
Yes, it's heavier than an AR10 but with the longer ranges, that's a good thing. Yes, it's not as precise as the AR10 either but it's the last US designed Battle Rifle and wasn't designed to be a tack driver. My M1A with NM sights is a 1.5 to 1.75 MOA shooter and that's plenty good enough for me.
Is it fun to own? Sure is. Is it fun to shoot? Absolutely. Does it kick like a mule? Nope, it's recoil is surprisingly mild and you can shoot it all day if you have enough ammo.
If you want it, consider it. Fun gun to own and shoot. Great look, heft, and feel. Great iron sights. The .308 is a decently accurate rd. Not quite as accurate as the .223 but accurate enough, and with enough punch (unlike the tiny .223/5.56) to be used as a hunting gun for anything in North American.
If you worry about the ammo cost, consider reloading. It's a great hobby and really cuts down the cost of ammo. Or, as I did, you can go a bit overboard and make yourself a .223/5.56 'Mini M14' so you can practice with the cheaper ammo. As a smaller brother for to my M1A, my 583 Series Mini-14 with it's thicker barrel is a sub 1.25 MOA shooter in it's own right. Besides, then you get to shoot both!
I shoot bowling pins at 200yds with both of them and with their NM irons (target aperture on the Mini with a thinned front blade), it's easier than you think with a bit of practice.
