If you want a serious business machine that can be relied on in European weather you need an IFR equipped aircraft that is allowed to fly IFR.
If you rely on VFR you will often be looking for another means of transport for your passengers, even in summer. Would you want high value passengers being flown in marginal weather, below cloud, or instead flown above MSA, in relatively straight lines?
It's not just the fact that twins have a fly away capability in the event of an engine failure, when flown to the correct profiles and weights. They also have duplicated electrical systems, generators, gyros and instrumentation and more sophisticated stabilisation systems, which can include auto ILS etc.