Going beyond all the agency debate, and DM requisites.
Walter suggests that being able to do basic ropework is essential for a DM. In many ways, things like this should be encouraged in all divers. I learned in a club where we had a PADI intructor who did everything for the enjoyment of it, and no money was made at any point (except by PADI obviously). We ran two boats (5.5m RIB's) these comfortably took 6 divers + a cox. From the very first dive I did in the sea I had to get involved in boat activities. Jobs like launching the RIB's from their trailers are much simpler when there are 6 or 7 people there all helping. Also, when we took the boats out there was plenty of other things to do, as walter points out, often involving rope.
In the club we had some very consciencious instructors and divemasters, and all the divers from the start got to do these things, even if it was with a DM patiently taking them through it. Did it make us better divers? probably not, but when we went on to do other courses such as the DM course, there was a much broader base of experience. Having had to help out on the club boat is different from having everything done for you by a DM, but so far it hasn't put anybody off diving because they have had to help.
(It also is a good way to lead into the Boat diver specialty dive as the first AOW dive, do the last two O/W dives, and then, after knowledge reviews, get the boat dive done before the end of the day)
This is just a different approach to diving. It is much less you being a 'dive consumer', but more of a lifestyle 'diver'. Also, with a good guide to where the sites are located you can get a weeks diving for less than £50 per person (we have collected some 5 - 600 different UK sites, and we now have GPS co-ords for the more recently visited ones, and transits and good diagrams for the rest) (excluding initial cost of boat - sports council grant, and maintenance - mostly paid through club subscription).
Different approach to diving? perhaps, but certainly enjoyable, as you get to see and experience other related parts of diving that mebe you wouldn't otherwise.
Jon T
