In the dive that I described taking off our weight pouches first and then our BCD to hand up to the DM in the boat were nessesary because we were exiting onto a swim step on the stern of the boat. There was no ladder to climb. We had to "fin up" our bodies out of the water, turn around and sit on the step, take off our fins and get back in the boat. Sea conditions would have made it very difficult to exit otherwise. I dont see any harm in doing that. It wasnt the first dive where that was needed. I dont have enough dives under my belt to say whether this is common practice or not, but I have done it on multiple occasions with multiple operators.
I don't understand the exiting proceures either ... sounds like a good way to loose your lead. We use weightbelts, but the idea is the same: we take off our belt and clip it to a line, we take off our tank and clip it to a line, we exit and the boat crew retrieves the gear.
I used both methods to get back in the boat. Both methods seem to work fine on small boats.