What’s exceptional is the near perfect alignment of lunar perigee, solar eclipse, new moon, and equinox, which is extremely rare. (Solar eclipses can only occur on a new moon, and new moons are generally associated with the highest tides of the month.)
The tides, however, are not so exceptional. Tidal response lags the lunar-solar driving function at Mont Saint Michel by about 36-48 hours. The March 20 high tide is 12.90 meters, just barely enough to flood the road. March 22, 8:28 AM will be 13.45 meters. February 21 at 8:47 AM had the highest tide of the year at 13.50 meters.
http://www.ot-montsaintmichel.com/en/maree-montsaintmichel-march2015.htm
http://www.ot-montsaintmichel.com/en/maree-montsaintmichel-february2015.htm
So, the hoopla is pretty much media bunk, but the astronomical phenomena is interesting.
Media Hype rules the day!