Depends on how you build it out, but yeah I do agree that Lync/SfB is the weak point in the suite. But the Exchange/Outlook combo is the gold standard for corporate communication.
No. It does not depend on how you build it out. Lync sucks, period, and has for a long time. Similarly, Sharepoint sucks irredeemably. It looks and acts like bad 1990s software. It's consistently the most painful, frustrating part of my workflow, and I use it as little as I can possibly get away with.
Next time you want to defend the full Microsoft software suite, just don't mention Lync and Sharepoint, and your argument will do better.
Sharepoint is a core part of it; and while I agree that Sharepoint is awful, it's a necessary evil that's better than the alternative.
Sharepoint just generally sucks because it's a platform for building one-off custom apps that part of your accounting department uses. Any platform with that use case is going to suck. But maintaining a Sharepoint environment is a lot easier than maintaining 30-40 individual web apps running on separate Linux machines, and it's a lot more maintainable of a business process than doing everything in an Access database or a shared Excel file.
It's also just flat-out ubiquitous. It really doesn't matter how much Sharepoint sucks because nearly every company uses it in some form.