BJJ is not a budo. It's just a series of techniques. It has no spiritual content. I am of the opinion that in Japanese arts everything has meaning and tradition. This includes the clothing and the protocol in the dojo. If you remove those things you might just as well go outside and roll in the dirt. Just my opinion.
So...if Morihei Ueshiba trained outside in normal clothing, as he was known to quite often, it wouldn't have been Aikido?