Re: Why do so many receipes call for eggs in the ingredient list?

In a single word - "functionality".

There are numerous ingredients that are used in foods because they provide 
a specific physical or chemical benefit without imparting any of their 
flavor.  Egg is an excellent example, since the subtle flavor of eggs are 
lost in many dishes containing eggs.

Eggs can provide the following functionality (not a complete list):
-  White when beat in low fat systems form a foam that helps add volume to 
products.
-  Egg yolk has natural emulsifiers that help stabilize water/oil 
emulstions (salad dressing or mayonnaise as examples) so the components 
don't separate as readily.
-  Egg yolk also has a vivid yellow color that can help provide yellow 
tints to finished product.
-  Egg white is an excellent moisture binder, helping to make products 
juicier and more tender.

Eggs are also an excellent source for many nutrients.  While not normally 
added for that reason, it is a definite side benefit.