The article and linked video are an interesting exploration on how why EMR futures may be in a modular design.

Does a single large group making everything work better?

It would seem to have some benefits including: standardised UI, quality control, a single unified application for interacting with healthcare

There are disadvantages as well: power, decision making and goals are created from a single group, and functional limitations of the chosen platform

From a separate perspective: Junior medical staff and other healthcare professionals often move between hospitals during earlier years of their career. The process of learning new programs, new structures and methods cause significant reductions in capacity early on in the transition. A single unified system could go a long way to improving those sorts of issues.

Does it make more sense for modular programs to exist?

I think unless incentives favour collaboration and standardisation, the benefit will be for single unified systems, because the tooling of the single system will have forcing functions which keep smaller projects in line with hospital/organisation, and generally will contain tools for creation of these new projects that a single IT/EMR team can become adept at improving and creating on.