Sam, why not use a 4000 reel instead of a 2500? Using your argument, it will do what a 2500 does.
If you agree you don't get the same feel playing a silver with light line on a 4000 reel as you would a 2500, then you should understand the difference between a 2500 and 1000
1000's are typically a fifth lighter than a 2500, but just to clarify 'balance': you hold a reel in your hand when it's on the rod, therefore 'balance' is not about the fulcrum type effect: if you were to place a heavier 4000 on your 11' Ultra, it wouldn't actually unbalance the rod on a pivotal basis, but it would numb the feel of the rod, its action and slow your reaction. Too light-a-reel can cause the rod to waft, but an 11ft light rod will almost be balanced without any reel attached! Therefore anything beyond the lightest reel possible is excessive and eating into some of the benefits of using that particular rod.
Retrieve rate is important: it brings the tackle in quicker, it can keep up with a fish racing towards you etc. The retrieve rate on a 1000 reel is relatively slower when compared to 2500. It may spin at the same rate but being smaller, one turn of the handle will typically bring in about 60cm on a 1000 to 70cm on a 2500. Yes the HG's will retrieve more but that's when additional drum speed can become a potential problem.
Spool size is an issue: smaller spools do have the habit of creating more line twist, esp when playing fish on the clutch. However, they do have the advantage of managing light lines better and the coil cast from the 1000 passes through the guides easier creating slightly less (but surprisingly noticeable) friction when using very light lines.
Power is required whether you play the fish on the reel backwind or on the clutch, to suggest a reel's power is unimportant is ridiculous. And yes, most anglers do crank silvers in.
The advantage of a 1000 reel is as I said, finesse. Of course, there will always be those who don't understand the joy of finesse.