Just an opinion - not a formal answer:
Replicate does what it does. Like it or leave it. For some things a improvement can be requested but varchar(max) to clob is day-1 decision and unlikely to ever change.
Replicate is a universal engine trying to replicate from any source to any target, or as least as many types as are commercially viable. Several targets do, or did not, have the VARCHAR(MAX) datatype or implement that as clob anyway and those that do on the source source side need to be handle much like clobs anyway.
My _guess_ it that Replicate simply picked a workable intermediate datatype. Unfortunately that datatype restrict certain functionality most notably transformations. That's quite a big limitation but most customers can live with it.
fwiw, in many experience varchar(max) is frequently overly used by 'just in case' simplistic (sloppy!?) source DB design. I've seen 'credit card numbers' and 'phone number' designed as varchar(max) - totally ignoring any source db performance and downstream consequences. Oh well
Hein.
