We usually make the distinction between lay practice and priest practice.
If you go in the direction of priest practice, then a kesa is needed. If you don't, you are already living in the whole kesa of the universe, as Sawaki Kodo says: there is no world outside the kesa. He means by that that everything as it is is already the kesa, and sentient and non sentient beings do all wear it.
So you are already wearing the kesa, and you feel-think you don't need it. That is perfectly ok.
I just would like to reflect that for some people here, there is a different story, another commitment and the light of that commitment, this sewn fabric is Buddha's body
If the rakusu is troubling you ... just forget about it and focus on sitting. Put your jeans on, even your hat and sit American style. No problem.
I don't think that Treeleaf have changed that much ( mind you, bear in mind that everything changes). Zazen is the core. The kesa as a clothing is the choice of some people
that want to commit further to the path. There is room for lay practice without a rakusu or kesa.
And there is room for people to discover by themselves that the kesa is also much more than fabric sewn.