Can someone explain to me the negative reception around Sniper Elite Resistance?

Correct me if I'm wrong, but it seems like many Sniper Elite fans are somewhat pessimistic on Sniper Elite Resistance because it looks like Sniper Elite 5.1. As in, it appears to almost look like DLC missions to 5 rather than a new game.

However, it seems like there are four very common complaints with 5 that could be fixed in Resistance. Those being glitches (poor performance), level design, too easy, and AI issues.

Sniper Elite Resistance is coming nearly 3 years after Sniper Elite 5. Why do people assume that a number of the core issues with 5 won't be improved upon with Resistance? Almost 3 years seems like a long time especially when you're working with the exact same engine and not bogged down with creating a ton of new assets.

Can any SE veterans talk me through this? I feel like optimism should be higher. What am I not seeing?