I would rather choose a different cruise line with different rules than have to eat somewhere other than the dining room for dinner. Those "other options" are fine, but formal nights are usually when the dining room brings out the good stuff.
And, I personally don't miss the old style formal attire at all. I grew up with it, and not only is it hard to pack, and expensive to fly with, but it is a pain to wear. I do not miss: girdles, stockings attached to garters, slips, petticoats, long gloves, etc., etc. I can't imagine wanting to go through all that on a cruise. Heck, the old style petticoats alone would take up all the closet space!