If you want something which can be plugged into a random network somewhere in the world and be reasonably capable of phoning home HTTP is your best bet for being not being firewalled.

There's also something to be said for using a well-known protocol rather than something obscure which is likely to require time to debug because it's had many orders of magnitude less usage.

Your point is valid, and you gave suggestions as well.

I agree with you that machines should not talk on the HTTP level, it's over kill. Machines only need very simple protocols to exchange current state if they do need to cooperate. To me, if devices can transfer state with the controlled program should be good enough so that the program will send the states to other machines for them to determine what's going to be the next step or directly give them instruction on what the next step to go.

I know it's a lot fun to build this type of cute machines, but it's not economic.

Our only use-case was ridiculously simple. I don't think CoAP or MQTT fit into that use-case, however at some point, yes we will add other protocols. Thank you.

Except it would be much harder to use and understand.

http is designed for "m2m use case"...

Hah! Never thought about it, but you are so right. HTTP is actually an M2M protocol at heart and is by far the most prevalent on the planet...