Dunno about how common it is but I don't use SSIS, SSRS, SSAS, Service Broker, or any of the other "add-ons" to SQL Server and I've worked for anything and everything from the proverbial Mom'n'Pop Shop up to and including a fairly hefty fortune 500 company. I do work with T-SQL quite a bit and do a fair bit of design and development along with my system responsibilities.

That, not withstanding, there are a huge number of "kitchen sink" job ads written for people who have a really good understanding of SQL Server at the system level along with all the add-ons I just mentioned. That being said, I'd have to say it's not so uncommon and I don't believe that it matters much according to company size although smaller shops would benefit more. I don't know of a big company yet that has turned someone down because they also happen to be good at SSIS. I'm pretty sure they'd find some way to leverage those additional skills even if the job wasn't strictly advertised as a "BI" related job.