The Rev. Jeffrey Steenson...

...is a former Episcopal bishop who was ordained a Catholic priest in 2009. Steenson is also married with three children.

An opinion piece in the Times today said that (my emphasis):

...the Roman Catholic Church is prepared to house married priests in numbers perhaps not seen since the years before 1123, when the First Lateran Council adopted canon 21, prohibiting clerical marriage.
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The Vatican has stressed that the allowance for married priests is merely an exception (like similar dispensations made in the past by the Vatican) and by no means a permanent condition of the priesthood. If a priest is single when he enters the ordinariate, he may not marry, nor may a married priest, in the event of his wife’s death, remarry.

Now let me see if I have this straight: For the first thousand years of the Catholic Church, priests were allowed to get married. But then they couldn't. And now today, if they become Episcopal priests first, they can then become Catholic priests later and stay married.

Why not just let them all get married?