This is something I would also do. I agree 100%. There are no rounds in real fights, it also gives unfair advantages that there is an automatic stand up even when a round ends on the ground, and also because it doesn't give BJJ practitioners enough time necessarily to work a sub.
On the flip side, you can make an argument that each round is like a mini fight, and that the guy who wins the majority of those mini fights wins overall. Then again a TKO/KO/sub ends it entirely and doesn't just grant victory for a specific round.
No ref in real life to stand you up or to end rounds, no cornermen to give you help, just you and an opponent.