There isn't enough of a GA industry in the UK to support the 1000-1500 hours requirement. The airlines wouldn't be able to find people and would need to look abroad.
Also we would end up with a situation where all instructors were building time, probably working for free or even paying to work and the career instructor wouldn't get a look in.
I do agree about the need for basic hand flying skills though.
I have read old accounts that mention airline flying clubs with subsidised GA type flying? Maybe more of this kind of thing is the answer.
As far as I can see the airlines do not support GA at all. Despite it being the training ground for a large number of their pilots.
The fact we have the MEP though and integrated guys dont even have an SEP means it is going more the other way