The waza is different, but I think there is still commonality that can be used to focus on certan principles. The beginning and the end of some of these techniques
look similar to Aikido suwari waza positions (the approx. 3 to 3:30 minute marks show what I would basically think to be good suwari waza; at 3:17 he even does some shomenuchi
This is a video
showing a sequence of ikkyo involving the kikyo foot position, which is similar to the shikko shape with the knees off the mat (the knees are nice for poking into the ribs too). I think it might be important because it's a transition point between standing and sitting kamae/postures. I believe it is important to be able to move between them, at will. Between shikko (horizontal hip/spine rotation around the central axis) and the strong vertical alignment of kikyo, I remember having a better sense of my "central pillar" upon which to rest the weight/force of my training partner, as well as to drive into them. Not that I was ever very good at it; but that was the sense I got from it. Hopefully others with more experience can describe what they're doing in suwari practice a bit more clearly (and with more authority) than I can.
Again, I am very out of practice
, so please forgive my somewhat ignorant ideas, but my sense of practicing shikko (stepping/walking in suwari) was that it helped me to think of moving with a stable base; using that base to displace my partner; it also helped me to clean up my hip rotation, which I'm now trying hard to reclaim (I'm easing back into suwari/seiza very slowly).
The bad thing I know of is the potential for wear and tear on the knees, which can quickly get pretty bad. I believe this can be avoided, but it's a pretty common problem according to some folks. Too much lateral movement within the knees, for example.
Per my studies of an independant form of Aikido, and lacking though I know my training is, I consider suwari waza to be a major part of developing various parts of the body to move with power. I'm not sure exactly how it would apply to BJJ, but I find the "combat base" to be a very compelling starting point for looking into it further, and believe the principles of a strong and supple posture relates regardless of the particular form of waza.
To my mind, suwari waza is only a half-step away from the foot-forward "butterfly guard" position I used to practice against with my friends. I like to practice kata while moving from tachi to kikyo to seizaho to anzato to newaza ("kohokamae?"). Each height level seems to inform the others with respect to maintaining that strong vertical alignment we generally try for.
My two bits, at any rate.
p.s. sorry if this is a bit jumbled as I'm juggling my wee lads while I type (my focus needs more focus).