If its important to modern Scottish people, why not be respectful? Ancient Celts did wear patterned woven wool, so continuing that tradition seems reasonable and enjoyable and could even be incorporated as sacred by modern Celts. I think that ignoring or dismissing current Celtic culture in favor of only the ancient is dissassociative. Tartan is a modern expression of long held Celtic values like family, pride and honor and a little local colour ;). As long as Tartans are not used as racist tools, and considering the value of fostering, they shouldn’t be, I don’t see any issue in incorporating them now. Celticists of any race, gender, and so on should be able to partipate if they honestly embrace the culture (learn some of the language, history, legends and values).
If you only like doing things like the ancients did you could weave or buy woven checked wools made with natural dyes. The sentiment could then be continued in a more historically reenacted way if you dig reenactment. I have noticed a difference between reenactment and reconstructionist. I think part of that difference is the importance of honoring the living cultures and participating in their protection and traditions. I appreciated how Kondretiev didn’t only write about the four feasts, but also wrote about the patron Saint days of those countries. Food for thought, I enjoy the conversation 🙂