Nowadays, one can only keep so many Mitzvos (271). That is less than half of the commandments of the Torah. I don't know if there is any statistic regarding how many Psukim discuss currently relevant laws in contrast to previously relevant laws (for example, how many Psukim discuss Tzaraas, Korbanos, and Tuma vs. Tzitzis, Tfillin, and Dinim).
Moreover, many laws became inapplicable towards the end of the first Beis Hamikdash. That means that there are many laws that were only applicable for less than 800 years.
Hashem knew that the Jews will spend most of our history in exile. Why is so much of the Torah written about things that will be actualized rarely, while many laws that are relevant for all time (for example, Tfillin, Mzuza) are learned from diyukim in scattered verses?