Why are modern dirt bikes and motocross racers saw horses?

i personally think the reason for it is because a straighter seat allows for better and faster seat transitions like when going from like whoops to a sharp turn

I totally agree, but I'm guessing they make em like that so that you can set the bike up the way you want... some riders like dips some riders like humps on their seats..pers. I hate the new yz's but thats the only brand I ride...

An interesting question John. Having started racing a long time before 'flat' bikes I found it hard to adjust to the 'new design'. At least on the 'old' bikes when you got a chance to sit you knew exactly where your bum was and it was supported ("wedged") in the right place.

It would be interesting to see lap times on identical bikes apart from the seat around a circuit.

I certainly prefer the dip seat but then bike designers aren't always riders, but that is just my opinion, and to get negative votes from people who don't have opinions anyhow. LOL...

Not totally sure but I believe that the design was from pro-racers (pretty much males) smashing their balls into that tank while running the gnarly whoopty-sections and asked for that 'hump' in the bike to be smoothed out.

With that theory in mind, it just goes to prove what wimps the modern pro-racers really are! ;D

It is possible that the dip in the seat meant that the frame had to be dipped which could havee made it heavier but i dont know for sure

In today's racing it is necessary to move all over the bike, not just be on the tank. Tracks and riding styles have changed dramatically over recent years.