The following was from Rav Aviner. These days, it seems to have become de jure, and it’s almost as if you feel “sorry” for someone who doesn’t have them each day. Would we be better off giving Tzedaka? It’s a difficult question as it can’t be generalised, of course.
Q: Is there an obligation to have Sheva Berachot all 7 days?
A: No. Whatever is most comfortable for the groom and bride. After all, it is to bring them joy and not to burden them (Re’im Ahuvim pp. 165-169. And Ha-Rav Moshe Feinstein related that when he got married they only had Sheva Berachot on Shabbat, and not on all 7 days as is customary today. Reshumei Aharon Volume 1, p. 18. And Ha-Rav Shlomo Zalman Auerbach once lamented this practice and quoted what the Chatam Sofer wrote in his responsa Even Ha-Ezer #122: “That someone once had Sheva Berachot on Shabbat and the entire community mocked him”, and that the Aruch Ha-Shulchan wrote in Hilchot Sukkah #640 that we do not have the custom to have Sheva Berachot every day. Meged Givot Olam Volume 2, p. 72).