Have you never used the Google apps on the iOS before ?

They are good but not significantly better than Apple's built in ones. Apple Maps may have less quality data but has a much better UI and uses a lot less data. Google Now is pointless compared to the genuinely useful Android version. Chrome is slower in most cases than Safari and not integrated with the rest of the OS. And really all their other apps simply aren't popular.

Unfortunately Apple just doesn't give third party apps any room to expand beyond its tiny little sandbox.

Android was designed to kill the smartphone business. Samsung is smart enough, and well run enough, to use Android and then discard it. Other Android OEMs are roadkill.

"By placing their apps on iOS, and essentially being the best of breed in every category..." I have to say that this is a stretch. Their mapping app is worse than Apple from a UX perspective. Granted the data is better, but Apple are improving very quickly in this concern. The Gmail app isn't even the best Gmail app on the platform, and their anti-user stance (getting rid of ActiveSync, not supporting push on other devices) is the only reason Mail isn't particularly great with Gmail. Conversely AS/Exchange, Hotmail/Outlook, Yahoo! and iCloud mail all work really well with Mail. The Google app itself is riddled with bugs that made the last update practically unusable and Now useless. The other apps barring Chrome, which does have issues but are out of Googles control, seem to be abandonware. For me, if you are already locked into the Google ecosystem, then Android is the obvious choice. However Google, IMHO, are playing dirty on this front.

"...they could all become fronts for Google's apps." Which would, IMHO, be disastrous for consumers and the open web. Google already have far too much control in the web space, getting close to ubiquity. Samsung, at this juncture, are the lesser of two evils. However, I wouldn't trust them as far as I could spit.