It is pretty easy to force flag spawn, unfortunatly not every one knows what to do or rather what not to do. I was unpleasantly surprised many times when my team outnambered enemies 2:1 and for example the only survivers on enemie team were camping tower in Native Village map, with a mauler or two. 3 minutes left to the end of the round and they keep attacking and getting mauled one by one ignoring requests to simply wait for flags in some safe spot keeping the distance from oponnents and simply do nothing for over 30 seconds. It often ended up with a draw or even our team loosing, becouse few folks refused to listen or simply can't be arsed to bother themself with waiting.
Making flags always spawn at a certain time would lead to even more camping and prolonging rounds. I would love to have fast, dynamic fights not a campfest.
For HAs, HXs generally cavalry is already affected with latest changes to Master of the Field script, if the last survivers on one of the teams are mounted then it triggers flag, so delaying the rounds and forcing the draw by last horse archer that simply refuse to die and prefers to annoy 20 alive enemies is pretty much impossible at the moment.
Back when I was playing Native, it was not a problem at all since almost everyone knows and understands how MotF works, so forcing it was never a problem.
Maybe small change to script would be nice, like removing part about distance so it would be easier to actually control flags. But making it always appear... I am skeptical about it.