I don't understand the objection to on-line either.
Here on the L&L in Yorkshire real Marinas are few and far between (either Chorley or Near Bradford) so you would have to trek 50 to 70 miles to one even though I can reach the canal in about 25mins. Even so the nearest mooring I can find (bottom of a farmers field) is 40 mins away. Yet bizzarly one of BWs business cases for the investment in big marinas is that people are prepared to drive further to them - surely thats exactly what we don't want.
We were actually in a marina for our first year - at Apperly Bridge - and it was great, easy car access, water, elec, security, boat shop, local shops now I walk across a muddy field and I don't save that much either. But the problem was it was a 1Hr 10 Min min drive (on a good day - bank holidays etc could be ages) and the route also went through 3 different urban area bottlenecks (rush hours, school run, speed cameras!). I actually have to drive round the country for my job so I am used to it, but regular trips to the boat were a real pain.
I would favour a mix of on and off line for different users. Again here on the L&L I have noticed a lot of places where small on-line mooring could be quickly and cheaply created (both on the towpath and other side) for those that want them.
I bet BW could even sell them with an upfront cost then x years 'free' mooring to cover the capital cost so there would be no capital outlay, and yet a basic concrete mooing with bollards etc would last years so they would easily make money from it.
I am also sure that some small investors would invest in such small moorings (say 5-10 boats) if BW would engage with them, it would be better for all than a buy to let property.
On the plus side when I was in a Marina I would reckon 80% of boats never left it, keeping the canal clear for cruisers, however I do think Marinas encourage a 2nd home mentality which may actually drive mooring costs up.