@xabean my machines have them built in, but with an extra spool of thread, it's faster not having to unthread/rethread the machine. In the case of my industrial machine, it really puts a damper in my rhythm having to rethread it.
@plinth yeah, I follow. I think I worked around that for myself by simply pushing the "need to wind a bobbin" further out by buying a 10pk of pre-wound bobbins. Only when I get low do I wind more