It is pretty cool seeing stuff you did in the old games relate to what is going on now in the game.. But I feel like they didn't expand on it enough for it to be solely the reason to play the next two games. The biggest highlight is morrigan and leliana, who both have a big role in 3. Alistair kinda pops up every now and then, and the rest are non-existent in the other games besides passing mentions. Same situation for your companions in DA2, one is returning companion in DAI, others are like oh remember them?

I would say the biggest decider on whether or not it's worth is if you performed the ritual with morrigan. However, the result of that is kind of just swept under the rug since it seems like they were predicting they were gonna use that in the next DA game. But since the original DA4 got scrapped and there's no real save import for veil guard and I'm sure the choices they allow you to make to are only the huge ones like morrigans ritual, it seems kind of pointless. To me, games like this shine when they remember the small details, a minor npc you thought was cool and randomly pops up again later on.

Ultimately my advice is the same as above; watch a YouTube summary, or if you're feeling really frisky, read the DA wiki on the people you're interested in.