Yes, Unreal Engine keeps getting improved, more Fortnite content gets produced. But there is a general lack of innovation, one that I find personally painful when I look at Epic's recent-ish track record. Needing to fire this many employees is not just a result of market conditions, but also a straightforward consequence of not being able to leverage them for sufficiently lucrative outcomes.
Companies with this amount of capital are well positioned to take multiple strategic bets which aren't at all safe bets, but pose no real financial risk for the company in aggregate. Why do these bets end up being taken instead by indies with much more to lose? Well, partly because indies often _need_ to take riskier bets to carve a niche. But the other side of the coin is, what I can only surmise, a lack of imagination and adventurousness on the part of management. They could be funding many experiments and seek to have another hit like Fortnite, perhaps in a somewhat different market. Having to seek another hit while your finances are declining is less pleasant.
When a company loses its edge in this way, as long as it hasn't _really_ captured a demographic or created some very sticky ecosystem, it's bound to get whittled down repeatedly. I doubt that Epic will suddenly get more creative and adventurous at this point, but perhaps necessity will have its part to play.
(Aside from all of that, I agree with most commenters here that the layoff is being handled about as gracefully as one could reasonably hope.)