That being said, Microsoft's new emulation is a completely different system to any ability to transfer saved games
Yeah, it is. They do, however, go hand-in-hand as part of the greater experience.
You put your save file in the cloud and it works on the Xbox One emulated version of the game. Now, that explains the emulated versions, sure, but the more complicated issue of transferring the 360 data into workable Xbox One data is probably a bit more complicated. That said, it has been done on several games to my knowledge. It would've have happened a lot more too if more developers put the effort into their "HD remasters".
As far as we're aware, the Xbox One version is a port of the Xbox 360 version with a certain amount of changed coding for Xbox One. For a niche title like this, one would imagine that you'd want to retain as much of your audience as possible, especially on a platform that is dominated by Minecraft (in this genre). Putting in the effort to allow players to move their save data from one console to the other should be mandatory for games like this. We're not exactly getting a discount on the Xbox One version for owning it on 360 either.
Furthermore, as I said earlier, a system (of sorts) is in place and I don't see Terraria increasing in popularity on consoles given how this feature is lacking. There's no point paying again for the game on a different console AND having to start over! Give the people who paid for your game last gen, and started all of their worlds last gen, some reason to pick the game up again on the current gen.
It's a necessary feature as it practically doubles your money for returning fans. Instead, you drop the ball and lose your audience. The longer you wait, the less people are going give a rat's
if you EVER do it! And future products? Yeah, you'll be the guys that only "sorta kinda supported their game, but every update was riddled with bugs and they wouldn't even allow people to move their saves between gens".
You may be a small studio, but it's been years and you don't cultivate a loyal fanbase by ignoring them. Do what you want with mobile, because that's obviously where the money is at now, but people will remember your failure to deliver on consoles. It's just that most have given up and moved on and are utterly indifferent to anything you do anymore.
So,
it!