Time for a reality check
...How many additional EF-S lenses Canon ever created for APS-C cameras?
Just 3 = 10-22, 17-55 and 60-macro?
The rest of EF-S family are 'kit lenses' for this or that camera model (18-55, 55-250, 17-85, 15-85, 18-135 and 18-200). These lenses were needed to make specific camera models attractive to some target users at some point in time.
Those who purchased 7D are supposed to use its 'kit lens' = EF-S 15-85. If they use EF 300 lens with 7D -- they are probably regarded by Canon as 'cheaters' who managed to get away from purchase of 5D.
Actually the selection of consumer-priced EF-S zoom lenses is a lot greater than EF lenses. If I counted correctly there are about a dozen EF-S lenses in the "normal" range compared to about four non-L full frame zoom lenses in the "normal" range.
Canon produced an excellent 55-250mm very low cost zoom exclusively for APS-C cameras. They've never offered anything of comparable quality and price to full frame users. Full frame buyers can choose from some very bad non-IS zooms, a mediocre IS version, an overpriced DO lens or an "L" lens. And that "L" lens has from the beginning been marketed equally to both full frame and APS-C users.
Yes, in terms of prime lenses, Canon has never done much for APS-C users, but some of that may simply reflect the changing nature of lens design and the market for new lenses. Most of Canon's prime lenses were developed well before the digital age. Canon has been slow to upgrade and modernize these prime lenses, so it's not like EF-S primes were being neglected while Canon was forging ahead with new EF primes.
Let's also stipulate that beyond about 75mm, there is really no reason to have a specific EF-S lens. The 55-250 EF-S IS being an exception to that rule. Any of the three 50mm lenses work fine as a substitute for an 85mm portrait lens. The 85mm, 100mm and 135mm EF lenses all serve as short telephotos... and so on up the line.
So it looks like: Canon never treated APS-C cameras too seriously. These cameras were needed and intended to bring new users into EOS system. APS-C camera users were supposed to purchase EF lenses (with existing EF-S lens lineup being so limited) and to make a switch to FF cameras 'some time later' (= now!).
Actually, these cameras were "needed and intended" to offer an affordable digital camera to consumers. Full frame sensor fabrication was just too expensive to achieve mass market adoption.
Canon and Nikon may have once thought they could move everyone back to full frame.
But, markets and technology evolve and companies aren't in control of that evolution.
The quality differences between full frame and APS-C are much smaller than most on this forum care to admit and for the majority of users under the majority of shooting conditions, the differences are imperceptible. On the other hand, the cost differential between APS-C and full frame, has not shrunk as much as some might have expected.
There is still a substantial "cost of entry" into the world of full frame. Even with recent price cuts, the cost differential between the 70D and 6D is significant and that between the 7D and 5DIII even more so. For much of the market, that cost difference will never be worth it for a small, perceived improvement in image quality.
And, for enthusiasts, that cost of entry grows exponentially for certain customers – such as sports and wildlife enthusiasts. If you are an APS-C user, you can buy the equivalent of a 480mm f4 lens for under $1,500, vs about $10,000 for a 500mm f4 for full frame. That's enough to keep many enthusiasts demanding better and more sophisticated APS-C cameras.
Regardless of what their initial intentions might have been, the reality is that the APS-C market is now too big and too independent for either Canon or Nikon to risk alienating and losing customers by not meeting the consumers' demands.