You're probably talking about really old versions of applications. I've been using SNI for half a decade without any issues.
Anything so old that does not support SNI probably still uses SSLv3, or maybe even SSLv2, so you really should be upgrading that ASAP, rather than keep supporting it.
If you take a look at the wiki article, there are some versions listed. Those are still in use. If our company forced people to use SNI, we would be out of business. There are TLS 1.0+ enabled apps that can't do SNI. Perhaps you and I are just in very different business models.
Anything so old that does not support SNI probably still uses SSLv3, or maybe even SSLv2, so you really should be upgrading that ASAP, rather than keep supporting it.