This would only be bad if you just do PUGs all the time. It's really not so bad if you take each person from your group and build their seals. The downside is the time and effort for just one person. However, like others have said, if these weapons are as good as SE hinted to early on about them, it's a hell of a lot better than building a relic weapon.

Unless.... these are like relics and this is only for the base weapon lol