with running to bot for a gank when bot is winning by a longshot? Does not compute.

Couple of possible reasons:

1- Top won and they have time to send someone to pressure/kill their bot and cap their point.
2- Top lost and can't seem to make it work, and they send someone bot to turn your lane win into a cap to divert ressources from top to bot so they can get an advantage top.
3- You've got an assassin on your team and that's something they should do.

A lot of it is I like to gank bottom lane when there's a lull in the fighting topside - ie, if we just won/lost windmill I automatically look to bottom lane to see if I can help with a gank.

HOWEVER that doesn't mean I run all the way down if it doesn't look like I can do anything, so that'd just probably be poor planning xP

Sometimes this is good, that is what people are saying. I beleive what you are referring to is the general mistake people make of failing to prioritize time and team placement.

What is with the obsession people have with running bot 1 by 1 when its 1v2+ instead of capping their mid 4v3-

I love the MMKH flowchart, that's why.

if top won and i have nothing else to do, i might as well go bot and do something.

Think of this way, is there something better you can be doing? How about ganking bot?

Because Apakhurst is there.