Just to let you know, Monzo are looking into aggregation too & I’d be suprised if they don’t offer it, as it’ll leave a big gap.
A ‘control center for you finances’ doesn’t make a lot of sense if it doesn’t include a view of all of your money, wherever it is.
Plus, adding the other accounts removes a barrier to switching for people who need to keep their legacy account open because they have a large overdraft, for example. Or for people who use a credit card from their bank & can see it, along with their current account, in their bank’s mobile app.