I didn't mind the window so much as how long it was. If the window was say only 30 minutes it would get pretty intense.
The windows in XI were usually 30 minutes. Too long considering there were 6 of them and like 90% of the time they spawned on the last one anyway. Do you really want to sit around and do nothing for 2-3 hours?

I also like the idea of an alternate means to fight, just so long as you can get the same rewards.