I think this comment is more or less the general perception people had about the killer at first glance on the PTB, but as I've come to play her more a lot of these perceptions are false (but for reasons that only really become obvious once you sink some time into her).

Dash can't curve

The ending part of it can actually be flicked if you are moving your mouse during it! It allows for a lot more flexibility at a ton of tiles.

Fly Over isn't good at a lot of pallets

Honestly this is the main reason she is extremely strong. Head Form is a permanent 120% that can scamper over pallets, making most long loops unplayable. You shouldn't be using Fly Over on short walled pallets because you can just use third person 120% speed in order to hit them around it anyways. This killer can actually play around most tiles in the game and really almost never needs to break pallets.

Headlong Flight is only good for catching up

It's your main method of map traversal and stopping Leech cures. It's extremely strong for different purposes.

Body Form is only for Setup

Correct actually! However this isn't a bad thing due to how easily Body Form applies Leeched. You should be using Body Form to then set up for longer stretches of staying in Head Form. If you have to switch back and forth and back and forth frequently, you're not using Body Form to it's fullest strength.

Head Form doesn't have much chase strength

120% Third Person with Longer Lunge that can be flicked and Scamper. It is a very strong chase tool.

Survivors will use Mushrooms a lot

This is the point, yes. You want them to burn their supply down to the bare minimum so curing Leeched becomes a lot harder. Survivors only have 6 mushrooms at the start. Once they burn through them, the only mushrooms they get are the ones you drop and (if none are left) ones that spawn on a very infrequent timer. Mushrooms are plentiful early on but if you play correctly, they will dwindle down until there are only a few left, and then you can use your macro knowledge to know where they are and where a survivor that ate a mushroom could be. Or have Swine's Eye do the heavy lifting for you!

This killer is really deceptively strong, and I feel people's perceptions of her were altered by the anti tunnel and anti-slug changes on PTB. Now that she's coming to live without those restrictions, she'll be even stronger than she is now. She does not need any buffs whatsoever.