Yea, but that seems to be because you see a few changes to graphics to be more substantial than meaningful changes to the actual gameplay systems. I'm stunned you'd actually bring Zelda into an argument like this... Halo 5 has done more to build on Halo 4 than Zelda has since the N64 days.
And hell, speaking of colour palettes, many Nintendo IPs not only have basically the same colour palette between sequels, but extremely similar colour palettes between different series as well. Cut random parts of screens out from various Mario, Mario Kart, Smash Bros etc games out, and I'd probably struggle to tell you where each is from (and probably even which gen if you run them through an emu).
Yes, you can shake up a franchise. That doesn't always mean you should though, rather than iterate on it and improve the things that fans want to see improved. Resident Evil 4 is basically a new series, lacking much of what classic RE fans loved about the franchise. Arkham Asylum, City and Knight have constant heated debates about what they've changed between each. I don't even need to mention something like Tomb Raider.
Again, if you want to see such drastic changes, then fair enough... this probs ain't for you... but you know this, and your "so what's different?" is complete insincere BS. You know damn well Halo 5 didn't somehow become an open-ended espionage game under your radar, so don't pretend that you're simply enquiring about it. If it were going to be a Resident Evil 4 situation, then you'd already know.
Again though, these are weighted averages. So you're asking groups of people for their subjective opinions, and then assigning a higher value to some of them based on the outlet they're aligned with (despite individuals not even having consistent view, let alone different people working for the same outlet). The weight in your example is something factual... people may not know exactly what it weighs, but they're all comparing it mentally to other weights that they've felt in common. And you'd consider each of their answers as equal. You wouldn't get one saying it's 2kg, another saying 5kg, and deciding that averages out at 2.4kg because you value the first guy's estimate more.