I can't say how important it is for meads, having very little experience yet with them, but with beer having temperature control of some sort is an absolute necessity, even if it's only a matter of choosing the right season to brew. Some ale yeasts top out at as low as 71F before they start spitting out excessive esters, and most will produce a lot of fusel alcohol if they get into the mid 70s, especially early in the ferment when there's still oxygen around. And the problem with fusel alcohols is that once they're produced they just stay around. I've seen wine yeasts with a much higher temperature rating -- into the 30s -- and have been wondering if perhaps those don't produce fusel alcohols for some reason.
I've seen a lot of different approaches to fermentation chambers. The easiest is to just buy a chest freezer and add a temperature control switch to it, though if you have the space you could buy a normal fridge and replace the door with a fermentation chamber. I went a little bit overboard on that myself -- my fridge powers a lagering chamber that gets down to about 2C, a serving chamber that holds 3 kegs around 10C, and a ferment chamber that can get two fermentation buckets or carboys down to 15C year round and below 10C for making lagers any time but mid summer. It's a great DIY project.