They do that. The range doesn't consist entirely on new models, lots of deliveries, weathered versions etc.
People will moan either way. Dapol do have a monstrous back catalogue to deliver on, I think it's reasonable to have a year consolidating and delivering, rather than heaping on more pressure to deliver.
On the one hand it's great for a manufacturer to say "we're releasing this, it's out now", but people want to (and manufacturers I'm sure like) feedback on CADs to correct errors and so on. The problem is that that happens right at the start of the development cycle.
Where I think Dapol are bad is that delays can occur so close to an ostensible delivery date. I get that it's really hard to say "this product will be available in 2 years" from conception, but to say "these should be out in 2 weeks. Actually, no, sorry, another year yet", as has happened with the 142, 50, mk3s, and I'm sure many other models.