As far as I am aware, this "A Jedi shall not know love" thing is new to Episode Two. The only explanation I can offer is that this is an example of what Dave said about Yoda's prejudices influencing Jedi Council policy. This edict against Jedi forming romantic relationships may be because Love makes you do irrational things, a weakness that Jedi cannot afford to have. How many movies have you seen where the Hero has the Villain on the ropes, and stops mere inches away from finishing the job because his True Love is threatened? I'm betting that happened all too often in 4000 years of Jedi adventures. I would presume that Crado's mate Sylvar going to the Dark Side in order to avenge him, and Quinlan Vos skirting the Dark Side's edge to rescue Aayla Secura, in addition to similar incidents we have not yet seen, would be seen as rationale for such a stricture.
In the two Tales of the Jedi instances you mention, I do not recall the Jedi Council as being so centralized and authoritarian 4000 years BBY (Before the Battle of Yavin)as seen in later times. The Jedi Elders on Ossus were nearly as large and averse to consensus as the Galactic Senate, so individual Jedi masters were given much more leeway back then.
There is also the matter of characters like Corran Horn in the X-Wing novels and Kyle Katarn in Dark Forces, who are children of Jedi. This would seem to indicate that the prohibition isn't enforced as strictly as Episode II would have us believe. Then again, these men are young enough that they may have been conceived during the Purge as a way to preserve the Jedi legacy in secret.