"but how can one company be expected to 'be the best' at everything?"
This argument gets thrown out a lot, and I don't agree with it.
First off, I would look at the current crop of VMS-only companies and relative to each other you might be able to label one of them as "best", but overall none of them seem to be categorized as clearly the "best" in terms of just overall product elegance and reliability.
The security market in general may not ever allow for an end-to-end "best" VMS. Do mall security cops have the same needs as monitoring stations? Do schools need the same features as subway stations? It's hard to make a universal "best" system.
Most of the end-users I talk to in the mainstream markets aren't looking for the "best" system, they're looking for the most cost-effective solution to their problem. They value reliability, ease of use, and overall image quality. All things that are not that hard to achieve (not that you would always come to this conclusion looking at some of the mainstream players).
On the topic of reliability and cost-effectiveness, there are significant advantages to what some might deem a "less than the best" manufacturer that provides an end-to-end solution. The components should be tightly integrated, and any major problems can be handled by a single tech support group, no playing round-robin support.
My personal opinion is that the stand-alone VMS companies are going to have a harder and harder time maintaining relevance and market share. That model worked 10 years ago when IP video was less mainstream and you DID have to focus on a narrow product in order to build something successful. These days I think the standard cameras are almost commoditized, there is no reason NOT to offer an integrated camera, since all the major R&D stuff is pretty much worked out. H.264 is the de-facto standard (maybe that will migrate to h.265?) and recorders are fairly well distelled also. So, why NOT become a full-feature company?
Milestone and Axis should just merge and get it over with. Genetec should buy IQInvision, or some other camera company they could get at a discount.