Usually when when the Ubuntu `sh -> dash' link is pointed out, it is meant as a warning to use the proper sha-bang, instead of just using `#!/bin/sh'.

If you're arguing that classic shell scripting doesn't carry you all that far, I would agree, but I don't see the harm in using #!/bin/bash or #!/bin/ksh in lieu of sh the few times you are writing a shell script; they are both extremely common and feature many conveniences.