Pasture Management Dilemma: To Mow, or Not to Mow?

Ugh...I've been battling an infection and side effects from the medicines all week.  Needless to say, I haven't been riding and am running low on post ideas so far. 

The pasture is out of control but I don't know if that's a bad thing. There are a couple of nice, cool-weather grasses and clover that grow like crazy in the spring. Since summer and fall was so mild, they grew again and bloomed like crazy, resulting in insane growth this year.  Once things warm up, they tend to die back and the weeds take over.

So, do we need to mow this to keep it under control?  Usually we do, but it pains me to see all that material to to waste. It's still providing nutrients to the soil, but it's not doing anything for the animals directly.  The first mow would normally happen before the clover and grass started to bloom.  Sadly, we only have a riding mower, so once it gets too high, we won't be able to mow anyways.

Left side is mowed, right side is not. It's even taller now. The llama is eating while laying down...lazy girl.

Pros of letting it grow:
-It will have a chance to go to seed to re-establish itself in the fall and next year.
-It's tall and I'm hoping it might smother out some of the hot weather weeds, even if it doesn't survive the heat. The sheer mass of the plant material should help somewhat.
-More for the critters to eat (with limits...so many limits).

Cons
-Once it gets too tall, we can't mow if we need to (when/if weeds start taking over)
-More difficult to ride in an enclosed area. Tall, tangled plants means increased chance of the pony tripping or some such thing.
-Might not do what I hope it will (smother weeds)
-Unintended consequences that I'm not thinking of???

We did mow around the inner perimeter to keep it off the electric fence, but that's about it.

So, dear readers, does anyone have any advice?  Should we mow to keep the pasture healthy? Should we leave it and let nature take its course?  I'm leaning towards letting it be this year. If things start looking bad, we can hope for the best and mow next year.