[B0rsuk]

Gandalf: for a start, try finding good sides of Light Cavalry. It's a hybrid of light infantry and awful archers, with mapmove 3. You don't pay 25 gold for an awful archer. You don't pay 25 gold for light infantry. There's no synergy between these two. If we exclude mapmove3 (Lion tribe infantry is just as fast!), well... You can probably Have one unit squad of light infantry and one squad of archers for the price, food, and upkeep cost of LC. And before you say LC is more flexible, you can send squad of LI and Archers in two different directions.
What I'd love to see is tactical purpose for Light Cavalry. Giving them stealth or pillage bonus would be nice, but does nothing to adress their battlefield uselessness. With the unrealistic +2 precision I proposed they could at least try fire&retreat, without risk of being engaged in melee. I don't think few volleys of overpriced( = low in numbers) archers would accomplish much, but it would be a good start.
I understand you have much more experience at this game than me. You should be more capable of finding a real use for Light Cavalry than me. I know many spells, nations or units eventually turned out to be quite useful in their niche, but LC is not one of them. If I'm not mistaken, Light Cavalry has consistently very little actual value since Dominions:PPP (which I didn't play).

I was toying with a mod idea. I wanted to implement early Dragoons (soldiers who'd go somewhere mounted, dismount at destination point, and fight as infantry). But I see very little point in that. As far as I know, foot soldiers have no advantages over mounted units in Dominions3. I could give dragoons Tower Shields and heavy infantry armaments, but I'm afraid the battle engine wouldn't benefit from extra mobility, if simple light cavalry can't.
As for dismounting mechanic, I could use shapeshifting.... if only I could attach arbitrary effects like shapeshifting to weapons, and make them shapeshift into footmen upon attacking something...