Actually, and I know I'm going to get a LOT of hate for this, but I actually like Beyond Earth better than VANILLA Civ 5. Time will tell how much of that like is "new game smell", and time will tell how my opinion changes when I get the expansions (which I plan to do), but right now, I have 91 hours of BE time clocked in (granted, it's a bit distorted due to the fact that I've been modding) and about 31 hours of Civ 5 time. There are things I love and hate about both, but so far I prefer BE. I've yet to try Civ 3 or 4, but I own both of them due to that insanely awesome Steam deal last month, but so far my thoughts are "Civ 5 and BE are good, but I just like Civ 1 better for some reason and I don't know why." (For those who don't know, I literally just found out that Civilization actually got sequels during that huge deal/BE free weekend, if you can't tell, I've been a console gamer for most of my life, and that's pretty much only switched around because I'm an indie dev now...)
As for Firaxis giving up on them, I don't think they have YET, like has already been said, we've probably got at least one more update due to Starships. As for other things, I'm hopeful that a new update, DLC or expansion (preferably update) will fix some of the more major problems like nothing but tectonic scanner option being viable, etc. and ESPECIALLY the lack of personality and appeal of the sponsors. Maybe it's because I'm still a low level player, but that's the biggest problem IMHO. Playing as China in Civ 5 feels rewarding and awesome, while playing as Pan-Asia in BE is...eh...okay I guess. Just okay. That's why I simply can't play BE without mods, nearly every custom sponsor has way more personality than all of the default sponsors combined.