"I wont roam" Says my midlaner.

Nope, it really isn't. Highly situational and some prefer to farm. If you don't take note of SS that's your own fault.

Also - watch your language.

{quoted}

Isn't that part of mids job, is to ROAM?

good lord...

no, actually it isn't.

It helps but its just a tactic

"GET READY GUYS, I'M ROAMING BOT!"

"Uh, ok......."

Walks past 3 wards, misses E, stands around stealing farm/XP

"WTF loser bot lane, I'm never roaming again!"

"..........."

Bottom line is, too much can go wrong if you decide to roam at the wrong time and in the wrong situation. Some mid laners are better off staying in mid to farm and push down their tower as fast as possible, at which point they can offer assistance to other lanes if need be. Karthus, Xerath, Ziggs, Vel'koz, Heimerdinger, etc. are all more useful when hard pushing. The first three even have global/semi-global ults they can use to affect other lanes if necessary.

Now, if we're talking assassin mids like Talon, Zed, Ahri, or Akali, then roaming (post-6) is a highly advisable strategy, assuming they've pushed out their lane. Snowbally assassin mids get far more out of roaming than their more stationary counterparts, especially if they've fallen behind. However this also depends on the state of the other lanes. It's no use roaming top, for example, if the enemy top laner is already 4/0 and bot lane is pushed in. You're just going to end up dying 2v1 top while the enemy team takes dragon and possibly a turret.

I pretty much never roam. It either goes wrong or there's never really an opportune time to do it.

If I'm playing against someone like LB and I see them start heading top/bot, i'm pushed in, and there's no vision where they headed, I'm absolutely not following them. I'll ping my ass off, but if you don't listen that's your own fault.