There was a comment on one of the cards that disapproved of nonbasics having a basic land type for no tangible purpose other than "just because". Even the Ravnica shocklands were criticized for having them.

So when is it a good time to grant a land a basic land type?

I think the shocklands were advertised as replacements for the original duals, so them having basic land types seems appropriate. It makes them more powerful and attractive and more like their predecessors.

But what about other cycles and utility lands? Why should or should not any land have a basic land type?

I'm not as against including them as some people, but it's rather hard to justify them, really. One of the only ways is to include them in a set our block where basic land types matter.

You mean nonbasics having land subtypes? I think what happens is that typed lands are generally very easy to get from the library. Generally R&D doesn't seem to like the idea that te manabase is so flexible as to make colored symbols in spell irrelevant, especially if those lands ca ETB untapped.

Of course this is by and large only a problem in eternal formals, but in so far as Wizards actively support Modern, I highly doubt the likeliness of seeing another set. As far as custom sets go, it all depends whether or not your design specs include that you intend your set to play nice with eternal formats.

As always - if you have a really good reason to.

The downsides are confusion and them potentially being much easier to bring into play that you intend.

Thge upsides are... um... well, it's much easier to bring into play. And you can save a few words, if you don't mind amping up the confusion.

Yep, Vitenka has it. The upsides are interacting with Forest-matters cards like Wood Elves and Misty Rainforest; the downside is interacting with Forest-matters cards like Choke and Acid Rain.

In real Magic, I and many other people would love to see more lands with basic land types. I think that's the problem. Wizards have been very, very cautious about it (the Sapseep Forest cycle was fine but not exactly a high power level), and the general expectation on Multiverse is "like Wizards except as otherwise stated", which in this particular case sets a very high bar. Most designs with basic land types (though by no means all of them) don't seem to meet that bar, making them seem more like wish-fulfillment.

I think I might have been the most vocal about this on Multiverse, because it drives me a little nuts.

I don't have a problem with the principal of adding basic land types in theory. I just want the designer to have a good reason why they included the basic land type besides "It makes the card more powerful/sexy." I can accept flavor justification, but the flavor justification has got to practically scream for it. After all, what makes your land more of a Forest than Karplusan Forest? More of an Island than Teferi's Isle? It doesn't make much sense for those cards to not include a basic type, but for a card named "Jungle Island" to do it.

As for mechanical purposes, I'm cool with that, too. But there's got to be a greater reason beyond 'This effect feels very green.' Sapseed Forest doesn't seem any more green than Pendelhaven to me.

The only time I've ever seen anyone use basics in an intriguing way for the land, mechanically, is one of Link's designs. I can't remember what it did exactly, but I think it was something similar to Naya Panorama, and operated something like this:

Land - Forest Plains
­: Add to your mana pool.
Sacrifice ~, , : Search your library for a Forest or a Plains, etc., etc.

That was cute, since players could (assuming a cycle) slowly wheel around the color pie, eventually fetching their Swamp. I wouldn't be thrilled to see them added to the game, but I wouldn't be upset with it, either.

Alternatively, I could see duals with neither flavor, nor mechanical application being added to the game if there was an obvious downside to adding the basic type. For example, a block that included 10 common lands that looked like this:

Land - Forest Plains
~ enters the battlefield tapped.
When ~ enters the battlefield, lose 1 life.
­: Add or to your mana pool.

Again, I wouldn't be happy with that, but I'd understand the purpose of what was going on. These lands aren't better just for the sake of it, but are filling a specific function in the game, while respecting the fact that basic, in general, means more powerful.

I believe jmgariepy is referring to Mangrove Beach, which, indeed, I meant to imply as part of a cycle. The cycle "justifies" its basic land types by the fact that they're all able to search for each other. I'm probably guilty of overusing basic land types on my lands, but there are a few where, looking back, I feel that it makes sense. That's one of them. Grove of Growth, Morphic Tidepool, and Scarred Valley are others.