Minhag yisroel torah brings from yismach yisroel a minhag for Rav not to darshan night of shavuos to show derech eretz kadmah LaTorah.
So we will speak about derech eretz.
It's quite a statement to say d.e. Kadmah LaTorah.
We say ilu kirvanu lifnei har sinai vlo nusan lanu es haTorah, Dayenu. R' Yeruchom & others explain, that for us to reach a status of being READY to accept the Torah is a tremendous accomplishment of its own! In spirituality we say only a keli malei is machzik - how full of maalos we were just to be a recepticle for Torah!
The preparation for mattan Torah seems like derech eretz. (see also medrash shmuel avos 2.2 t.t. w d.e. Refers to peace & brotherliness with others. - this works well with vayichan) R' Yeruchom though points out that reishis chochma Yir'as Hashem.
However the two are not really different. As a matter of fact from b.k. 92a its clear that Avraham's claim rak ki ein yir'as elokim bamakom hazeh - was in response to Avimelechs asking about Sarah - which Rashi calls a lack of Derech Eretz.
what's the connection bet. D.e. & Yirah? The simplest form of Yirah is recognition of limits. That I am not free to do anything I feel like. That same self restriction or discipline can be on a non relidous level - derech eretz, or on a more lofty level - yir'as elokim.
minhag yisroel Torah brings birkei yosef that when haman blasphemed the Jews to Achashveirosh, he also said "they set up assabim on shavuos..." what's the lashon hara about that???
I'd like to say the title d.e. means that even on a non-religous level, eretz, - which seems hefker & without restriction, also must have a derech. A road that has definition, limitations, guidlines & a goal. Even before Torah & religion, the simple world around us needs some form & guidlines with boundaries & a starting point and destination. The world must be recognized Not as a 'hefker velt' even from a non religous perspective. Eretz has a Derech, & its possible to be 'off the derech' of derech eretz besides for being non religous.
Achashveirosh wanted to show the Jews that even the material world can be enjoyed & used without limitation & with no purpose. (This was to show that not neccessarily is there another world of eden.)
Haman looked at the Jews who take the most 'hefker' disorderly, unlimited natural product of eretz - assabim - wild grasses - (he didn't say flowers) & place them near the Torah on Shavuos showing that all of nature has guidlines & requires disipline in their use and a purpose! Can there be a greater antithesis to the ideas of Achashveirosh!?
Beyond d.e. KADMAH laTorah... There is also the Torah's specific guidlines how to use the world on an elevated plain. That is the 'Lachem' of shavuos - how Moshe Rabeinu debated with the angels for the Torah.
Let us use the lachem of Shavuos properly. The yesod v'shoresh hoAvodah intsructs very stongly that when we sleep & eat on shavuos it shouldn't be 'regular'. Rather full of Joy & thankfullness to Hashem. don't allow the eretz of the 2 days of Shavuos to be 'hefker'. it should at least be with discipline, guidlines, - on a derech. And perhaps even elevated - to a means of ahavas Hashem.
