Is anyone else having this trouble?

My horse is an aggro monster. All random encounters seem to target and focus on my horse. And on occasion my horse will go on a killing rampage (putting herself in considerable danger) leaving me running around like crazy trying to kill everything before they fell her.

Is this working as intended? Is my little pony actually some kind of rare Nordic berserker horse breed?

Yes, THIS. I've just given up even trying to protect her, and once I'm killed everything I cheat and type "resurrect" into the console. I'll keep this up untill the horse mods roll out.

Yes we need horse armour

The horse is barely faster than running anyway. It's less fast if you often have to stop, dismount, fight a mob, remount, continue.

I gave up on the crappy horse system in the game =(

No horse for me until I get bored with all the cool stuff to watch as I walk.