If you look at Regondi's old tutors, you'll find that he changed bellows direction far more often than most modern EC players - and that was for classical music. It's in the later Victorian tutors that longer legato phrasing became the unquestioned norm.
Given that we're playing an instrument with a relatively limited range of expression compared to, say, the fiddle, it seems to me that we should add as many expressive effects to our repertoire as possible. It doesn't mean that we have to use all of them all the time, but it does give us more musical choices.
The physics of a bellows change does give a different kind of emphasis compared to a staccato button press or a pulse of the bellows in a single direction, so it's certainly worth experimenting with its tasteful use.
Anyone who believes that you can't execute rapid bellows changes on the EC should listen to Simon Thoumire's bellows tremolo - it's fast, controlled and rhythmic. It's just a matter of practice. My suggestion would be to build up gradually to avoid strain injury.
I personally like to add as much lift and drive as I can when playing trad dance music, and I often work the bellows pretty hard. I was once at a session where some of the musicians were round a corner. At the end another concertina player popped round to say hello and was surprised to see me playing an EC - he thought I was playing an Anglo! After all they both have similar reeds and bellows - it's mainly the keyboard layout that's different. So with the right technique there's a wide overlap between the sounds you can achieve.
For someone like me who plays a lot of Scottish music the EC is more practical than an Anglo, because we play from 3 flats through to 4 sharps. And I appreciate the ease of playing legato for airs. But I don't see why I should have to give up the wonderful drive and lift the best ITM players achieve with their Anglos. And players like Simon are living proof that the EC can equal the Anglo for dance music if you put your mind to it.