I don't know that the term 'oversight' is appropriate here. DNSmasq not only provides DHCP services but it is also the foundation for a number of services which required a functioning DNS server. The services include:
...and every single update including security updates.
Simply stopping in essentially breaks a number of things. If you are skilled enough to compensate for these by properly assembling a replacement or by over the architecture of the DNS of the server with some replacement then it will also be trivial for you do the other types of things that does whatever it is that you need to do. Some of these other tasks include:
Disabling the consumption of port 53 by DNSMasq by setting the port parameter to '0'.
Rolling in Bind and DHCPd from ISC because you want to use them instead.
The purpose for not having the start/stop button is to save people from breaking essential functions of the system. Feel free to do it manually but having that button NOT there is a good thing and will save a lot of heartache for those people who don't know/realize that the DHCP services is also the same thing that is making it so that there server can run DNS resolution on their updates.