I mean...as far as value goes - sure they aren't worth as much now. But if they go up and there's a large sum you are holding = not bad. You're also correct in that I could trade for those too but that's also another layer of expenses for exchange fees (not to mention time/risk/etc).
I'd like to point out that exchange fees are negligible compared to the extra rewards you get. Let's take F2Pool for example. Their website says that they offer a PPS system with 4% fee, plus 1000 DOGE for every LTC mined. At the time of this writing, 1 DOGE is worth about 0.000055 LTC, which means that the extra dogecoins add about 5.5% to your payouts. This gives an effective PPS ratio of (1 - 0.04) × (1 + 0.055) = 101.3%, far lower than the 108% we're currently offering.
I've said before that most of the miners I've received feedback from don't want to have to worry about multiple currencies; I'll add that those who do, generally prefer to diversify their portfolio themselves rather than holding on passively to whatever merged mining yields - which I think makes sense, as it gives you infinitely more options. Given this, in my opinion receiving payouts in a single currency actually makes things easier.
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