"can seriously raise the transaction costs of joining up"
What does this mean - in English - please?
Can "transaction costs" (?) be jokingly raised?
How about just designing simple systems that do the specified job, at the specified cost and on time? If, later, integration is a requirement and experience shows the real problems derived from lack of it cannot be solved any other way then consider the best way forward.
The proposal for more meddling by the ignorant numpties is really just a plea for more consultancy pounds to fix problems of inappropriate original specification and design.
But, hey, what do I know?