Why not just have the pioneer be the settler unit? It makes sense; as that is what pioneers are. Older civ games worked that way and it was fine. It creates tension, do I want a second city or do I improve my first?
The question is, what is going to happen with the settler's equipment? It is my understanding that it should be consumed by the process of founding the new settlement
Vanilla actually has the ability to make pioneers consume tools when founding colonies, but it's unused and disabled in xml. I removed it because the implementation was questionable and it turned out that it was buggy and could be used to get professions without paying the cost (scouts without horses, pioneers without tools, military professions without weapons etc), but you would gain the yields when the you let the unit join the colony afterwards, essentially free tools, horses and weapons. This exploit was possible even though the feature itself was disabled in xml.
The fact that it's in vanilla indicates that paying tools to found colonies was considered by Firaxis. They decided not to use it, which might be due to the implementation, but it might also be due to not liking how it affects gameplay.
I am not completely against a few of these events. (e.g. Python or DLL-Diplo-Events)
They add flavour.
But they should not be used to simply kill all strategic decisions needed by the introduction of this change.
Because that would actually make the change in the mechanics pretty pointless again.
That's why it should be tied to difficulty level. Sure it might make the mechanic more pointless on the introduction level, but the mechanic is introduced and on more difficult levels the player will not get such free gifts, or at least fewer of them, which makes the game mechanic relevant.
Master of magic got the difficulty level right in this regard. The easiest level is game breakingly easy. For instance you can find unguarded mana nodes. When you play on a more normal difficulty level (not even hard, just not intro level), then they will all be heavily guarded. However because you know the benefits of using them from the intro level, you know harvesting the mana makes your magic so strong that it's worth aiming towards beating the guards. If you started out with only strong and (for a new player) unbeatable guards, players would be more likely to skip this part of the game entirely.
New Players will most likely start with TAC which is perfect for new Players.
TAC isn't being updated. WTP is. That alone means it's possible that people start out with WTP. Making sure the introduction level is in fact an introduction for new players would be the right choice. If it means giving the player gifts, which breaks certain mechanics because it makes the challenge too easy, then so be it. We should have an intro level, which isn't meant to be played after you have tried it a few times.
In this case if the player needs settlers to found colonies, give the player a few settlers to try it out. This way the player will know the mechanic and what to aim for when later playing a more reasonable difficulty level where the player might not be given such gifts.
Writing this makes me realize we might want to add a difficulty level called tutorial, which will include extra popup windows and stuff like that.