It's insane. I swear that some liquor stores I go to have a craft beer section that's 90% IPAs... and another 5% that are basically IPAs with cutesy names like "Super Duper Pale Ale."
They take less time to brew than a pilsner so when you only have a small capacity you can churn out more product if you're targeting IPAs. This is generally why (beyond the general trend) microbreweries will opt for IPAs over lagers.
I've brewed both styles. You're right that lagering adds a step and not doing it adds significant time to the brewing process, but in terms of the volume at a brewery, that's really only a one-off time delay. After it's in a brewing rotation, lagering doesn't add time to a production schedule. It's more about storage space and equipment at that point.
IPAs can be significantly more difficult to brew, so if you're talking about a one-off brew, IPAs are harder to make WELL but faster to brew. Pilsner is easier to make well, but can take longer and/or require an additional step (lagering).
Had the same thought to myself at the Sprouts today. All I wanted was a stout. Not even a Guinness anywhere, but an entire wall of IPA's and then the rest were hard seltzers.