except that urgot is a ranged bruiser

The OP's suggestion will just translate into a 5 bot scenario until top was unlocked, at which time 4 of them leave for top with ensuing poke war at top as always. Or some variation thereof. Wouldnt change a thing just delay the inevitable.

I think that Windmill fight is actually a good thing for Dominion.

There are a lot of people who claim that Dominion helps develop the skills important for Summoner's Rift. I think the Windmill fight is one of the reason why Dominion players tend to have good team fighting skills, especially at the high elo play.

Both team channel the Windmill not in the hopes of capturing but in hopes that the other team will lose their cool and make a mistake. During mid-late SR games, this is incredibly important. There are games where people lose because of one small mistake. The Windmill recreates this in a weird way.

In the beginning, it is 3v3, not 4v4. This represents a lot of team fights. Very rarely will you be in a situation where your entire team is together. It will often be small skirmishes where both teams are less than optimal. Both teams are all level three and lack their ults. It is pretty much equal footing, no one is fed so you do not have that one super-hyper-carry that can single handedly win an entire team fight . Everyone has to do their part in order to win or at least stay alive.

Then the team's fourth member joins the fight. This can turn the tides of battle. If your team did terrible, they might be able to turn things around. If your team did well, things might change. How will you use this fresh champion entering the battle to maximize your advantages and minimize your disadvantages.

At higher elo, people will use their revives to jump back into battle. Suddenly, it is somewhat of an endurance contest. How long can you keep your cool and prevent yourself from making a mistake? Stay in formation (position) and take advantage of everything and anything you can to win.

If you win Windmill, what do you do? Do you stay and defend or recall and come back stronger than before? This trains your decision making skills.

This one small windmill fights captures the the spirit of team fights. This is what makes Dominion so awesome. I just listened to the recent Dominion Breakdown and I think the guests stated that their team did lackluster during the laning phase, but their superior team fighting skills more than made up for it mid-late game for them to win because they transferred the skills they learned from Dominion into SR.