I don't think the pattern should be broken.
If a nymph is to get a new ability, the element would need to get a card to go with it.
Nymphs are too rare to give them an exclusive ability, and breaking the normal pattern would set a bad example.
However, I can't imagine a simple little buff in stats would really help. If it was a 3/6 (upped: 3/7) creature, would people use it? This would put it equal to life's nymph, which has a pretty good attack and health for a nymph. I don't know that I would, even if I had them, except in very very specific situations, as in I had a deck planned around nymphs.
The nymph could not get much, if any attack buff, simply because it can multiply with its ability, so something like time's nymph (6/8) would be too good. It could get more life, but, then, still, it has to be good for the ability, not its stats.
That's not to say the ability has no potential, but it is unlikely that new cards will ever change how we see the ability, due to the fact that it works only on pillars, and unless it creates at least 2 nymphs, nymph's tears would be better. It's not impossible for the current ability to be good, but considering there is plenty of room for the game to grow, there is plenty of room for a new card AND new ability for the nymph.
I'm not a terribly long time player, but the post for the light nymph is from 2 months before the post for hope, so I imagine those are the times those cards came out. That would mean that people started using that nymph for a deck that became possible only later.
I want to state this very carefully, because I am no expert on this game...I cannot imagine a situation where this nymph could be useful, when compared to just having the nymph wanted, or nymph's tears, except for downright OP cards (something that gives +1/+1 to creatures for every identical card in play, for instance).
That doesn't mean that such a card doesn't exist. It may exist, and it may make its way into the game, but my personal view is that us mere mortals are better making suggestions about what is currently in the game, rather than what could be, but hasn't even been brought up. If something that could create a combo with this ability is on the forum somewhere, I will gladly read and may change my mind about the potential of making nymphs using a creature like this. If it doesn't, are we meant to think of balance around potential future ideas?
Anyway, to bring a long post to its end, I don't disagree, the pattern should not be broken, but there is no reason to bring up the pattern if another idea could fit it. Introducing a new card to give a nymph a new ability would be a big addition to the game, but so long as a card with the ability were to come into the game, as well, the pattern would not be broken, and, unless there are card ideas, or cards in development, that will make the ability good, like hope did in your example, not changing the ability would seem to be balancing around potential future ideas, rather than current cards and card ideas.