Martin Würthner and Peter Naulls are very unusal in the RISC OS market of being independant programmers working almost full time on RISC OS (although Peter now has a real job), they are also extremely dedicated individuals. This enabled them to commit to very big challenging project, and their excellent reputations from past achivements ensured people would trust them by contributing cash towards the development costs even though the code is under GPL and must be made freely available.
Unfortunately theres not may others like them, that have the time or inclination to take on such projects. Most programmers just work on much smaller things that interest us when we get the chance (which can, as pointed, out lead to a plethora of small programs all addressing the same purpose). I would hate to see the situation where programmers starting with the best of intentions take people money for this "ransomware" but are unable for whatever reason to deliver on the commitment.
So although we have two very successful examples of how this can work, we need to be vary careful before jumping on this bandwagon. Ideally any projects taken on should be by a small team of programmers to prevent one individuals change of circumstances derailling the project. Meticulous attention must be payed to project planning to ensure that there is sufficent programmer resources to complete the task in a reaslistic amount of time, and also to be able to show potential investors how their "ransom" money will be spent.