You can throw forward with a very specific diagonal angle on the control stick. It is too difficult to be consistent, harder than Brawl and it was already somewhat tricky there. I think Link still has a glitch where it's easier to throw it forward. I asked the Link Boards last November and it's still old tech to them.
Yup, Link can throw it in all directions just like in Brawl. We call them bombslides and personally I can do forward consistently. That's the most useful direction of bombslide as this gives enough extra distance for Link to actually true combo on the bomb hits with with Zair, Fair, Nair, Up Tilt, etc.
Anyways this is just an item DACUS.
I can confirm the timing is different for Megaman as I just tried it. I could not get a single forward item DACUS to work. I don't think it should be harder to execute the forward variation for Megaman but the timing is different.
When it comes to item DACUS you need to time the dash and then time the throw itself along with holding the direction to control it. Having use to main Link in Brawl and Project M I imagine Links are just more used to DACUS in general and are more practiced in this. It probably shouldn't be any easier for us to execute.
Edit: I should probably add the forward variation of bombslide for Links is significantly harder than the up variation. It took me weeks to do it consistently and even now I still have occasional misses. The tip for anyone trying this is to consider remapping their control to do this easier or to do the inputs differently.