SCCS started out as single commands, and many of us learned to use that way (I still do - for simple things I still find it easy to use - including as the front end to all my troff).   Anyway, a couple of the SCCS macro commands tended to be used together or in sequence and that is the key step.   When Eric started to use SCCS for development of Ingres in the late 1970s, as Larry pointed out, Eric wrote the BSD sccs command wrapper.***

That said, I'm not sure Eric's sccs command was the first time I had seen tool wrapper, although it may have been the first "tool" wrapper as a C program in that sense.  I have some memories of a couple of others that were shell scripts, but I can't remember any specifics, other than the C compiler itself (cc was originally a shell script) and the original man command.   I do remember looking at what Eric did when I first came across it, as I recall I had to mess with it -- may it did not run on the 40 class systems without some hacking - I really don't remember why.  

I think the key is that shell scripts were becoming more and more things we wrote with every day and more and more tools became scripts.   But on the PDP-11, the shell was limited and took resources, so converting from a shell script to C program was not unusual for speed.   The next step was things like Eric's sccs command.

Clem

*** As an aside, it is an interesting question is how the SCCS commands and CPIO sources originally made it to UCB.  Those tools were part of PWB 1.0 and 2.0 - which was not released to Universities - although Mashey had published at least one paper about it and was an ACM National Lecturer at the time.  Hence, many people knew about SCCS (I had heard him talk about it 1979 at conference in Oregon).   Anyway, other than those tools, I do not see much other evidence of PWB's specifics in the UCB archives.   I've always guessed it was an unnamed "OYOC" student that left them there or it may also have come from the Joy/Kowaski - uMich connection.  I don't think it was Ken because Ken wrote tar so he is unlikely to have left cpio.   But Ted was always fan of cpio (and may have had a hand in its creation).    We'll probably never know ;-)  I certainly had become familiar with the PWB tools a few years earlier at CMU, via the same type of path "OYOC"  (either Phil or Ted) - which is also why so many of us knew about lots of the work at AT&T - it was pretty well written about and published.