A homogeneous bid is good for giving immediate information to partner. However, you must also make proper use of your ability to refine the description of your hand later.
It would be very silly to play a system in which no hands were ever opened 1S. After all, we only have a very small number of opening bids to work with, and not to use one of them would be a terrible waste. That much is obvious. But in a similar way, suppose that in your system there are no hands which, after opening 1C, would rebid 3S after the auction started 1C : (1D) : pass : (3D). Surely that is wasteful as well. In order to make maximum use of the space available to you, you would really want to make sure that not only are all the opening bids given meanings, but also all the rebids as well.
This is why homogeneity is not always a good thing. If you tell partner all the important information with the opening bid, then that's great for helping him make an immediate decision, but it leaves you with nothing else to say later.
Of course, it is not always possible to make full use of opener's rebids. If you expect partner to pass your opening bid a large proportion of the time (as for example with a 1NT opening), you cannot expect to have the chance to rebid. So the rebids cannot be defined. Having this sort of opening bid in your system effectively decreases the total amount of space available to you. This may be a problem that you are willing to accept (I quite like natural 1NT openers myself), but it is still a problem.
The difference between one-bid and two-bid hands comes up again here. Opener's high-level rebids can only be used on two-bid hands. So, if you want to make full use of the space available in each opening bid, then these opening bids must each contain a fair number of two-bid hands.
Limiting the strength of your opening bids is bad from this perspective. An extreme example would be a 1H opening in a Strong Diamond system, which might show about 8-12 HCP with 4+ hearts. Hands in this strength range are hardly ever going to be two-bid hands. So after any reasonably high-level competition you would have to make disproportionate use of pass. The other rebids may get used very occasionally - and would therefore be very descriptive when they do come up - but the vast majority of hands will not be further described. To put it another way, there will be fewer sequences in your system available for the genuine two-bid hands (because none of them start with 1H), so these will not be described so well.
In contrast, a "standard" 5-card major opening, with a range of 11-21 HCP or so, makes much fuller use of the two-bid sequences (arguably too much). The beauty of this bid is that it is on the one hand a nice homogeneous bid (partner knows about the 5-card suit immediately) but there is also plenty of potential for making descriptive rebids.
It's important not to confuse this with arguments about the frequency of the opening bid. Indeed, trying to analyse systems by looking at the frequencies of their opening bids is very unreliable. For example, suppose you were to play a 1C opening showing a balanced hand with 10-13 HCP. Then this has a frequency of about 15% in first seat, much higher than standard systems which typically have 1C openings with a frequency of 10% or less. However, this 1C consists of a single hand type with no two-bid hands, and so hardly any of opener's rebids are utilised. So we might say informally that "you are not opening 1C enough", but really this argument is not about pure frequency at all, rather the number of different hand types in the opening. You could easily add, say, all 20+ HCP hands to this 1C opening. Indeed this could result in quite a respectable system, as we shall see later.