I’d say this is the smallest of worries, as there are ways around this.
The question we need to ask is what content we want to see exactly? Bear in mind that Infinite Flight does not support buildings or other 3D objects properly, etc. so add-on scenery wouldn’t do much (plus we already have a form of this through the Airport Editing project).
Aircraft: sure, it would be nice, but as Jan said, there are still limitations on mobile, especially in the context of Live, rendering multiple objects at the same time. All add-on liveries would need to be standardised (same format, same resolution - this is why custom liveries now are against the T&Cs). I’d also say it’s a bit premature to add custom aircraft.