I think one of the huge problems here that has not been addressed is that the initial training is so (SO!) expensive, that there HAS to be a return on the investment.
There is much criticism of people who "wish to jump straight into the RHS of a shiny jet", yet little understanding that generally people would LOVE to go instruct for the first 1000 hours. The problem is of course that when the average (f)ATPL costs what? £50k? a £12k salary as an FI just does not cut it.
THIS is why people need to get to the reaches of reasonable salaries as quickly as they can and this is in turn the driver to go direct to jet.
As Night FR8 has stated, I think also that (Beak in particular) people assume that PTF is nothing more than chequebook selection. I seriously doubt this is the case - in the recent easyJet selection of OAA cadets I know for an absolute fact that to even be considered, you had to have >85% and first time passes in all ATPL exams and first series passes in both CPL and IR. I know that if you were put forward to easy you had to go for interview and selection. Alright, >85% these days is nothing particularly special and first series passes doesn't mean that much either (except that you still have to achieve these and all of us that have done those tests would have to concede that's not necessarily easy!). You can also argue that perhaps the selection at easy wasn't as vigourous as it would/should have been had the candidate been selected by the company for a fully paid position, but either way, hardly "unselected".
That said, I do fully agree with Beak that selection should be purely through ability and your fit with the organisations M.O., not through whether you can pay or not.
However, IMHO - a defined "apprenticeship" type scheme where the route to RHS looks something like CPL/ME/IR --> FI 1000hrs --> FO turboprop --> LHS Turboprop --> RHS jet etc (not arguing whether that's right or wrong, btw) would benefit all....but the key is that training has to be priced such that the earnings you can make at your appropriate career ladder rung mean you can survive - this is the biggest single detractor from this.