there are always several reasons to have a missile in a tank. Not if the missile compromises teh tank gun design, but if an tank can get a missile=guided shell, why is wrong?
A missile could be used to threat a helicopter, or to hit a tank at ranges too great for the gun. Obvious that the modern tank guns are enough for the most types of targets but if the "western " guns are so perfect why the Israelis offers guided missiles for tank guns? Why there are so many types of guided ammo for artillery, naval guns, etc?
i think that the Shillelagh and the ACRA were wrong concepts,
1. No, there aren't. There is one reason to have a missile in a tank, and that's if the gun (or it's ammo...see Number 2. below) is inadequate to the tank defeating role.
2. Air Defense has been tried, but is a mission better performed by vehicles, or men, armed with dedicated weapons suited to that purpose. As to:
"why the Israelis offers guided missiles for tank guns?" ...because not everybody has current generation tank guns or access to DU penetrators.
3. Actually, Shillelagh was not a "wrong concept", but it was a crappy execution WAY ahead of the existing technology and one baby step behind TOW, which is better. And the M81 gun without the combustable case available at the time
would have had some real potential in a heavier vehicle than the Sheridan...and maybe even there, in some applications.
Missiles on tanks aren't bad, just not necessary... if the gun/ammo combination is adequate and available.