There's a pretty big difference between the games you listed and games like Fallout 3, XCOM and Syndicate. Renegade was never considered a sequel or reboot of the C&C series. It was a spin-off released while more traditional sequels were still being made.
Semantics. The reality is that Syndicate was a dead brand that has been revived, just like Fallout 3. Nothing was being done with them. Now you could argue that they're better left dead than remade like this but Fallout 3 was very well received and it remains to be seen what happens with the new Syndicate.
And even if it is a terrible game it may be good for the brand. Afterall, Tribes: Vengeance was crap but the poor reception and criticism lead on to Tribes: Ascend, which looks to be much better. We can always hope that this game - whether good or bad - will bring us one step closer to a true sequel. Afterall, if this game doesn't sell then the IP could be shelved for another 10yrs, at which point you'll never see it revived again. Very few 30yr old titles get revisited.