Why not subscribe to the mailing list and make your suggestion there? The link is above, and it isn't in any way closed - and AFAIK because everything is really in the early stages, discussion of ideas and possible routes to take is welcome.
Speaking more generally, as a developer I release some software with a price tag, and some I make freely available - in the former case, payment from such a system is inappropriate, since users are paying for it anyway, and in the latter case, if I wanted people to pay for it, the price tag would be something other than £0.00, so I'd neither want or expect any kind of payment from a venture such as this.
However, not every developer is the same, and nobody's background is entirely the same; from what they can spare in terms of development time, to what their abilities are, what help and support they need and in what areas - and right through to their motivations for coding.
I therefore think the motivation behind RISC OS Connect is a good one and worthy of support, and that's why I am on the mailing list - primarily only as an observer or interested third party, though I'll comment and offer help where I can. I would urge other developers, even though they may feel as described in the article about benefitting from the project themselves, to do likewise.