The most compelling reason to replace eggs is if you don't want the ice cream to taste like eggs. Even then, you can do fine by reducing the number of yolks—which is generally what I do.
I wouldn't consider all those ingredients egg replacements, though. Most pastry chefs use some kind of stabilizer blend, even if they're making a French-style ice cream with a ton of egg. Such a blend might contain all those ingredients, or everything except the emulsifiers (the gylcerides).
While the stabilizer blend looks like a lot of stuff, its advantage is that it works in minute quantities. By weight you'd use between 1/10 and 1/30 as much as you'd use egg yolk. So you can get the texture modification of egg without the interference in flavor release, or the egg flavor itself.
Some people look at modern ingredients like these as "additives." But if an additive is an ingredient that doesn't contribute anything you want toward flavor, I'd consider egg yolks additives in ice cream. Then it becomes a simpler question ... which additive to I prefer? The yolks or the powder?
