> A lot of their recent product development has been to enable further expansion in organisations - "Dev Mode" for developers (which now looks incredibly quaint against LLMs), […] all are about expanding their TAM out of "pure" design.
I don't think this is correct. In my experience no one buys Figma because of Dev Mode only. Dev Mode just makes it easier/faster to go from an existing design to working code. So it is/was a means to increase Figma's moat, not to get new customers or users. (Devs already needed access to Figma before the introduction of Dev Mode.)
Yeah in my experience the ones who benefit the most from dev mode are junior Frontend devs - the ones who don’t know how to implement a pixel perfect design from static comps. Dev mode gives you a head start on the values to use for some css properties, at least, and maybe a more visual way ti experience the css vars in a design system.