The key is the interpretation of よろし. It means "commonplace / ordinary" in this case.
とて is an adversative conjunction when the main clause is negative or a rhetorical question, as same as ~からといって / ~という理由で.
Are there those who think cherry blossoms are commonplace because they bloom every spring? (= No one thinks so.)
BTW, I know you omitted さて at the beginning of the sentence. It's not used as a conjunction like the one in modern Japanese, but means そうやって "like that (= cherry blossoms bloom like that / like as everyone knows)" there. My two cents.