I would much prefer technology to mitigate or even improve over time currently undesirable features. In a larger map with much more swamp, rainforest and dense tropical forest (jungle), there should be a way to represent both the human encroachment on these ecosystems e.g. rainforest deforestation, and the limited draining of wetlands, without it being the only prudent decision to immediately chop all these features the moment it is possible to, with the only exceptions being planning for your one national park or playing as Congo. Even though sadly this would seem to be a realistic representation of things, in actuality habitat destruction of said ecosystems is an ongoing process that is push and pull, with massively increasing public sentiment against it. However in a recent game as Indonesia, for example, apart from my one national park city the moment i researched microbiology there is only a benefit to chopping all rainforest.
An interesting suggestion would be to give these features a benefit similar to how coast benefits the solar panels improvement: plus one food to adjacent tiles (but the rainforest tiles themselves have a heavy malus such as -2 food), with a maximum of +1 (no stacking). This would encourage the player to create a realistic model of land usage where forest ecosystems become smaller and fragmented over time, but there is obvious value in keeping them around.
When I played as Arabia I found solar panels extremely useless. It's a very late technology, and by that time the number of possible specialist slots are plenty and it never worth to work these tiles even in costs.
So I guess solar plants should somehow turn more desirable to build.
And about the swamp and rainforest/jungle, yes we can say that they aren't any good at the moment. The point is valid. But at least jungles can be cleared while swamps are always there which isn't realistic at all. I mean we have the technique to drain them if there's a will.