The value of experience has indeed been dulled down. It now longer affects missile damage, and now you only get +1 attack/defense for being on bronze chevrons, 2 for silver, 3 for gold; rather than +1 for each chevron.

However units still get +1 morale for each chevron.

I'm not sure on this, but I think experience may increase missile troops accuracy.

And yes, the Alchemists Guild upgrading thing is a bit strange and pointless.