Hey Mario, welcome to the community!
Talking about the separation between Investment Banking and Retail Banking activities- The Glass Steagall Act was enacted specifically for the same in 1933. You can hear some of it in @Vivek_YS 's Talk here:
Also as a customer myself I would be more comfortable in having one custodian of all my money and understand where you are coming from.
A wide variety of asset class to choose for while investing is what I gather as an ask from you!