Non-jet hours are not useless - in fact there are old crusties like myself who would prefer to employ pilots who had a couple of thousand hours of 'real' flying under their belts, as we recognise that there is no substitute for experience.
But we are not the ones who employ now. Recruitment is all in the hands of Beancounters, Human Remains and Shrinks.
Beancounters want pilots to self-fund type ratings and work long hours for little remuneration.
Human Remains want pilots to touch their forelock and show that they will do as bidded, without ever questioning authority.
Shrinks need to be convinced that the candidate possesses 'soft' skills like empathy, has faith in all beings and knows the value of a high five or fist bump after every landing.
Above all - and quite reasonably - airlines want the candidate to be trained THEIR way from day one, not come in with preconceived notions of how it should be done.
The longer someone flies single pilot in the likes of a King Air the better pilot he or she may become, but also habits and expectations will develop which may not be to an airline's liking or 'culture' .
Properly trained 200 hour cadets have shown that they can master modern jets to the extent required of a co-pilot.
Hence, you either make the move to airlines as soon as you can, or risk being shut out . There is nothing to be gained by becoming 'overqualified' and much to be lost by squandering potential seniority.