It's just too many hard monsters at the start of the game. You used to face a lot of easy monsters at the start - things that ran away, things that spawned more guys, things that dodge you - all monsters that aren't very damaging. Now you have snakes that do a CRAZY amount of damage that you can't even avoid by leveling up or clearing a floor, you stay poisoned, plus bear traps that damage you, plus robbers that can take food or gold bags from you. It's just way too many harder monsters added.
Actually snake poison is cleaned on levelup and the poison is not cumulative which mean if you hit two snake in a row you will suffer 2 damage total and may avoid most of them by leveling up before. The muncher drop a single trap so if you hit 10x of them and trigger the trap later you get a total of 1 damage which is basically the same than hitting 10x blobs. The scrounger is indeed very annoying but it's a lvl 2 monster you need to compare it with turtle or goblin for example.
I think the real problem is the lack of a real easy mode so player have a place to learn how to deal with this impresive monsters without dying every 2 minutes. I'm currently working on this part.