I downloaded Adventure Island on WiiWare this morning and was pretty shocked to see that there were huge black borders so the game played in 4:3 not widescreen!

Is this the case for all Hudson games? It seems pretty rubbish to me.

I don't think it is (though to be honest I don't think I own any of Hudson's WiiWare titles).

It is a retro-style game in their defense (though Sega did a full-on retro game in Pole's Big Adventure and that was widescreen, so go figure).

As soon as I switched the game on, I was immediately surprised to see the aspect ratio. The only other game I have had this with on WiiWare so far was Mega Man 9, and it isn't usual for Hudson to release games like this, no.

Well, as someone else explained 2D games let you see different things at different aspect ratios so it makes sense to force them to use the same one on all TVs for fairness (otherwise 4:3 users would see more vertically and/or 16:9 users would see more horizontally).

Wario Land Shake Dimension does the same thing just with prettier borders (that also display the secondary mission goals).

I think it would make more sense to make widescreen the default though and use borders to make it fit on 4:3 TVs, but I say that because I have a widescreen.
Still, unless the game heavily features puzzles which seeing more of the screen would enable you to see things you aren't supposed to, I don't know that seeing farther the world in an action game makes a huge difference. Certainly it would make a difference, but I could live with it.

It's a remake of a game from an era where everything was 4:3.

You could see enemies earlier, I think it'd affect fruit spawns (since fruit spawns only when it scrolls into view), you could see bosses from further away and generally people won't like having one group have an advantage in a game with online leaderboards depending on their hardware.

Ah, here is where I must shamefully reveal that I haven't played the series except for a few rentals when I was a kid, so I don't remember it almost at all. I was just speculating based on platformers in general and don't really know about fruit spawns or the fact that it has online leader boards.

I like most of the Hudson games but this appears to be just lazy programming...