Why couldn't Hashirama break through Edo Tensei like Madara did? Hashirama Senju was the legendary ninja in the world of Naruto, he was also the only one who managed to defeat Madara Uchiha.

How come Hashirama could not break the seal of Edo Tensei (when Orochimaru, who was less proficient in Edo Tensei than Kabuto later on) much like Madara did with Kabuto? It seems silly that Hashirama who was stronger than Madara could not break Orochimaru's seal, while Madara was able to break Kabuto's more powerful seal.
Hashirama doesn't need to break the Edo-Tensei because it's already mentioned that Orochimaru (Jutsu owner) is not able to control Hashirama. 

Which means he is already acting on his own free will. The only risk is if someone catches Orochimaru and undo the Justsu somehow (like Itachi did to Kabuto), all 4 Hokages will vanish. Even in that case, there is Edo-Tensei grace period. During that time, Hashirama can break the Jutsu and recast it on his own, same like Madara did (maybe 2nd also, he is the Jutsu creator).