No, you absolutely don't. My friend just won a gold medal at GABF this year for his English Pale Ale, and his 15 bbl mash tun has no temperature control. I did it with a cooler and a screen for years before having this stand built and going with a kettle, which, initially, I wrapped with gym mats and metal tape. That worked fine, but mash temps dropped, especially when I began a recirculation.
All of my upgrades to my system since I got my process dialed in on the first system years ago have been about convenience and making the process move more quickly (shorter brew day). While the bells and whistles of automation aren't necessary, they don't stink, and I enjoy not worrying about hitting my dough in temp precisely (I shoot a little low now). I also don't miss the times I would forget to turn off my HLT and boil my sparge water. Seeing how many times the TOP cycles to maintain precise mash temps, I don't think I have the patience to babysit it. On my system, it would definitely require more than two cycles in the hour.
But your point is well taken. You can make great beers without it. However, the beers you can make with it are pretty amazing, too.
My first brew stand. I look at that picture fondly, but I don't miss the process.