Creature Type: This is nice, and hopefully will allow more variety with PC races. Still wish duel creature types had made it in though.
PvP is a table concern and should be decides by the table and not the game.
All right, all right. I understood what you meant and I agree with it.
Alignment: I like these changes as well. It makes it more clear to the DM that they can change alignments around how they want, rather than every single member of a species being exactly the same.
It actually doesn't make it more clear at all. Saying it in a stat block is just as clear as this...
"The alignment specified in a monster's stat block is the default. Feel free to depart from it and change a monster's alignment to suit the needs of your campaign. If you want a good-aligned green dragon or an evil storm giant, there's nothing stopping you."
That's just as clear as these changes. Reading that it's crystal clear that they can change alignments around how they want, rather than every single member of a species being exactly the same. The only real difference is that now DMs who didn't bother to read the alignment section of the MM have been catered to. Personally, I have no sympathy for DMs who didn't bother to read the alignment section and see this as an unnecessary change.
Tags: Cool I guess. Interested to see what they have planned for this later on.
I have no opinion on this right now.
Proficiency Bonus: Omfg I'm so happy that this is in stat blocks now. It just makes it so much easier to reference, and a nice aid when homebrewing monsters.
This I'm also happy with.
Spellcasting: I'm torn on this. I like the idea, but I think there needs to be direct rules clarification on whether 'spell like actions' can be treated like spells. So for example can they be counterspelled? Can they be silenced? Classes and abilities which focus on shutting down offensive enemy spells might end up basically useless from now on.
Crawford has said that all of the best combat spells have been made into actions. Unless the books are coming with errata that allows class abilities and spells such as Silence and Counterspell to work on them, he has rendered these abilities almost completely worthless. The spells you'd want them to work on are no longer spells.
Ability Score Increases: I've made my opinion clear many times, but evidently WotC are determined to go down this route which I hate.
Same
Age/Size/Weight: If I used all the explicit words to describe exactly what I thought about this change, I'd probably get banned. So I'll be slightly more polite about my thoughts on it.
It's awful. Like so awful I can't describe it using civil language levels of awful. I despise it. Everyone is now just a reskinned human, all living the same length of time, and weight. Why have different species at all if diversity is apparently racist? Just remove everything but human, and give a list of abilities to pick from at the start.
I want to go on a much longer and angrier rant, but need to keep it short so people don't have to read a wall.
Languages: I like this change. Languages aren't innate or biological, and any species should be able to pick any language. A 'suggested' language would be nice though, to show what's most commonly spoken by that species.
On the other hand, unless a Bugbear was raised by Elves, it's going to speak goblinoid, because that's what that species speaks as a whole. Individual exceptions can be handled by the DM. They should have default languages, but perhaps with language like is now in alignment indicating the DM can depart from it, not that a DM should need it.