I mean 2425 gold for 6 armor, 6 all stats, 25 movement speed, 1.75 mana reg is really not great, even if the move speed stacks. Not terrible I guess but you can always buy better items instead. Solar Crest is only good if you can use the active of it, and multiple Solar Crests don't allow you to use them multiple times.
I'm pretty sure it's intended since they explicitly thought of it for Wind Lace and included it in its tooltip, why wouldn't they think of the same for Solar Crest.