The people who have been asking how strong Simon would eventually become in the grand scheme of things have been making me think that it would actually be really interesting to see the Cradle universe from the perspective of a character that isn't from Cradle eventually. Especially given how broad the outside world's powers seem to be, compared to the relatively narrow set of powers Travellers have. So it would be interesting to see Simon go beyond the Traveller's Gate world (how does the limitation of Valinhall's chains interact with the seemingly unlimited power in the outside universe?)
Mild spoiler alert, but if you're this deep into this thread and you still care about spoilers...RIP you.
Eventually, we'll get to see how the Cradle magic system stacks up against others.
Also, Valin gathered the Valinhall powers essentially by running around outside.