[Avodah] Rabbinic system vs. ethical integrity

[Daniel Eidensohn]

There is a dispute in the fourth perek of Bava Metzia between R' 
Yochanon and Reish Lakish concerning aquisition of objects with money. 
R' Yochanon holds that money is  a doreissa technique but it was 
invalidated rabbinically to ensure that the merchandise being purchased 
would be protected until taken by the purchaser. On BM 47b the gemora 
tries to refute Reish Lakish who does not accept money as a doreissa 
technique. It argues that it only makes sense that beis din should curse 
someone  retracting from a deal involving money - which is good on a 
doreissa level - but is only invalid on a rabbinic level. The curse 
makes sense because it prevents people from taking advantage of the 
rabbinic invalidation of kinyan with money. On the other hand the gemora 
initially states that it doesn't make sense to curse someone just 
because he doesn't keep his word.

The conclusion of the gemora which is brought in Rambam and Shulchan 
Aruch is that the mi shepora curse only applies in cases where there was 
some transfer of money. Where there was only a verbal agreement then 
there is no mi shepora but only a statement that the chochomim are not 
happy with someone who breaks his word.

Question: Does that mean that -
1) Preventing people from taking advantage of a rabbinic ordinance is of 
greater importance than the mere ethical consideration of keeping one's 
word and that's why a curse is used to protect the rabbinic system but 
not to prevent breaking promises?

Or

2) Does it mean that keeping your word is so obviously important that it 
just needs the awareness of our Sages disapproval of breaking 
commitments. On the other hand preserving rabbinic improvments to the 
system is not so obvious a value so it requires a curse to arouse 
awareness of its importance?

Daniel Eidensohn