Service Packs ain't what they used to be...
Back in the day, service packs were important as they ensured everyone got the fixes and fingers-for-the-dam that some might be without, if they weren't obsessive about manually downloading and installing patches As such they were important and the odd (or huge, in the case of XP SP2) extra service/utility thrown in just sweetened the deal and made installation compelling...eventually at least.
However, in these Windows Update times, a service pack just isn't bringing much to the party as just about everyone's Windows install is (should be?) patched to the hilt.
And as I recall Microsoft stating that they were not keen on including any significant new functionality in future service packs, the installation of a service pack seems like a bit a belt & brace operation nowadays, rather than any reason to become engorged.