I don’t think it matters what era, scale, or prototype you are modeling - if you want a fleet of highly detailed, decent performing locomotives bought off the shelf, it’s going to cost big $$. It was true in the heyday of brass steam models, and apparently it’s still true for diesels - where the numbers on the proposed roster are even bigger.
The trade-offs remain the same, too: 1) accept more work and time on your part - trading $$ for time; 2) accept lower standards of detailing and/or performance - no sound, Athearn BB, etc; 3) accept a reduced roster.
There are some very interesting posts here about the differences in business practice, east v west.
I think Kato would have done better to look at what sells well in the HO market, and thats first generation diesels.
Kato have stuck doggedly to more modern prototypes, and as a result (straw poll coming up) neither I nor anyone at my club own a Kato loco solely for this reason - price and quality are not issues. Atlas Athearn, P2K, BLI have all picked prototypes from varying eras, and have reaped the rewards as a result. Sure I’m not buying an SD70 / 90 (whatever) because its way to modern, but someone who is doing modern image might be tempted to buy an SW7 for that industrial plant’s switcher … and while your at it I’ll have two please … problem is Kato are now way too late and the market has been flooded.
Bachmann and BLI have understood this and switched their attack to steam where there are so many prototypes to choose from they will probably never swamp the market (unless its a Pensy K4).