As annoying as the Factorio biters are, they do provide a little bit of pressure that keeps you wanting to research new things and continue building. (They also inspire a burning hatred that will drive you to research and implement ever more efficient methods of murdering them). The same goes for the limitedness of Factorio resources patches.
In Shapez the logistics that come with expansion and defense don't exist, so it winds up feeling sorta samey. I like the chill, relaxing vibe of Shapez but eventually felt like I was just doing the same things over and over with slight variations.
Also, the lack of a blueprint book in Shapez is a major drag. I ended up setting a map marker way the hell out which lets me "teleport" to an area where I copy/paste designs from, but that's pretty hacky and ruins some of the flow state that Shapez lets you cultivate.
All that said, I've been following the dev of Shapez 2 and at least visually it looks awesome, so I'll definitely be hopping into that at some point.