I say...Yes they are just as important. The cooler the water...the more O2 will be carried to the roots and keep away the evils. I'm in Louisiana so the temps are quite high so I keep my resovoir temps between 65 & 70. I usually sit around 68f most of the time just to split the differnce.
I grow tomatoes also in Hempy Buckets and have incredible fruit. I started growing tomatoes years ago and got the hang of it after a couple years and it's made the jump into cannabis much easier than I thought. Tomatoes are a real bitch to get right so I think that prepped me the best. I started growing cannabis for my wife that has Stage3c Ovarian Cancer so everything I grow is critical and so far I've had amazing results.
I also use Chemgro 4-18-38 Tomatoe Formula (like many large scale cannabis growers use now). It's got a great balane of nutes and I adjust the formula during the Veg Cycle with Nitrogen to get my growth done right. Then I back off the extra Nitrogen during Flower and supplement with a bloom kicker. The Chemgro is from HydroGardens and is really cheap and is ONE formula instead of all the wild Consumer Pimped stuff that's sold these days. I also use 100% Perlite instead of any mix, but did have great luck with CoCo/Perlite (50/50).
Anyway...I guess that's more than you asked for, but I was just feeling Blabby this evening...