As you’re aware that wasn’t the model that supported Trainz for the vast majority of its long life. Until the subscription model came along, everyone had the opportunity to get the same feature set for the same price.
The flip side of that is that those who use Trainz enough to make a subscription worthwhile are saying that the retail version should never be feature equivalent and those who prefer that version should always be denied the choice of having the latest features.
Surely TLR and imposter system are still in development? Plus N3V have made it clear that the retail version will not have all the features that the 'equivalent' Trainz+ even at release.