The quirky study of the chronology of the Passion recently published by Sir Colin Humphreys claims that his "discovery" that the real date of the crucifixion was April 3rd solves the problem of the variability of Easter. Of course, as soon as Humphreys adds "Easter Sunday should be the first Sunday in April", you realize it was never going to be quite that easy. The first Sunday in April might well be before April 3rd, after all?
The date of Easter has been controversial almost ever since there has been an Easter. In the second century, at any rate, the first serious dispute erupted when Christians in different parts of the Mediterranean realized they had been interpreting the meaning of Jesus' death in two different ways. One group simply continued to celebrate Passover, but with the new meaning provided by the passion and resurrection of Jesus. This practice gave precedence to the lunar calendar which provides the months of the Jewish year, and on which observance of Passover must be based. Since they celebrated on the 14th day of the month Nisan (or its local equivalents), these Christians became known to others as Quartodecimans, "fourteenthers".
The other practice suggested that the days of the week, which roll forward independently of months and years, also needed to be accounted for, since Jesus was raised on the first day of the week, Sunday. Hence the celebration should be on the Sunday after the celebration of Passover. This pattern won the day, doubtless at some cost to the sincere and reasonable commitments of the losers, as well as with the loss of the more immediate connection with Passover - in fact, a desire to distinguish the now predominantly-gentile Church from Judaism may have been influential in this process.
The relationship between months and years, as well as months and weeks, has made the date of Easter complex. Since months in Roman reckoning lost their connection to the phases of the moon but were calculated variously according to local customs, it was deemed necessary to specify that the date of Easter not fall before the equinox (as well as to reiterate that it was a Sunday) - this was one of the results of the famous Council of Nicaea. Hence the familiar pattern: Easter is the Sunday following the first full moon (the 14th day of the lunar month) after the vernal equinox. However since the equinox and/or the moon might be observed differently depending on your location, the problem did not go away entirely until standardized tables were developed and circulated.
This held as a more or less universal way to set the date of Easter until the adoption of the Gregorian calendar in the West in the 16th century. The Eastern Churches generally retained the older Julian calendar, with the result that Easter can again be on different days in the eastern and western Mediterranean, and elsewhere. Attempts to find a common date continue, but conservative elements of the Eastern Churches have already fulminated and split over modest attempts to re-align the calendar.
The idea of a fixed date is therefore doomed to founder on the lack of agreement that would arise among Christian groups. A fairly serious attempt to fix the date of Easter was made in the UK in 1928 but was abandoned as impractical - it is no closer to being realistic or appealing today.
There are, I suggest, at least three reasons Colin Humphreys' suggestion will be quickly ignored. One has already been given, i.e., that any fixed date will only find limited acceptance. A second is that his research is unconvincing, based on mistaken premises about the character of the Gospels as history and about related issues concerning Jewish sources. Third and most important, I suspect, is that Easter is not commemoration of an "anniversary" - it is the Christian interpretation of a feast more ancient than the death of Jesus, from which Jesus derived part of the meaning of his death. The obscurities of calculating this date are a reminder of the world from which this feast comes - not one of bank holidays, but of harvests, full moons, and the remembrance of ancient liberation.