the stigma of not offering korban pesach in the midbar

Rashi writes that even though the opening parsha of Sefer BaMidbar occurred chronologically later than the the parsha of korban pesach discussed in Be'ha'alosecha, the Torah reversed the order and placed the later parsha first.  Why?  There is a stigma attached to the parsha of korban pesach because there was only one korban pesach offered in the midbar -- Bnei Yisrael failed to bring the korban the other 39 years -- therefore the Torah did not want to open the sefer on a negative note.

Tosfos (Kid 37b) explains that Bnei Yisrael neglected the korban pesach all those years in the midbar because they held like the view that the mitzvah of korban pesach applied only after yerusha v'yeshiva, after the conquest of  Eretz Yisrael.  The korban offered in that first year in the midbar was a special hora'as sha'ah command by Hashem.

If so, what is the stigma attached to the parsha?  Bnei Yisrael had no obligation to offer a pesach, so they didn't -- what's wrong?  Tosfos answers that Bnei Yisrael didn't look good because they should have entered Eretz Yisrael right away.  The only reason they spent 39 years in the desert was because of the cheit hameraglim.  

Tosfos shifts the stigma away from a direct association with korban pesach to the failure to enter Eretz Yisrael in a timely manner.  The Maharal, however, stays true to the course and writes that the stigma is directly related to the mitzvah of korban pesach.  True, the korban could not be offered because of the extenuating circumstances of ones in that they had not yet reached Eretz Yisrael, but being subject to ones, having an excuse, even a good one, is just not the same as getting the job done.  Ones is a ptur onshim, an exemption from punishment, but it does not remove blame or stigma entirely.

Seems that the point of contention between Tos and the Maharal is the classic question of whether ones is a ma'aseh aveirah with a ptur or not a ma'aseh aveira.  Tosfos holds that if there is an excuse for not offering the korban pesach, there is no stigma attached with failure -- there is no ma'aseh aveirah.  Maharal, however, holds that there still is wrongdoing even sans punishment. 

The Sefer Maor HaTorah quotes a Chasam Sofer that even though usually we say if an act is not done due to some ones it is not considered k'man d'avid, as if done (the point is actually a machlokes in the Yerushalmi), mitvzos aseh are an exception.  The gemara says explicitly that if one planned to do a mitzvah but due to some ones was unable to, Hashem gives the person schar as if the mitzvah was done.  If so, even if the Maharal is right that usually an ones still is a ma'aseh avira, but here we are speaking about a mitzvas aseh of korban pesach -- why then would the desire to bring a korban not count as if the korban was actually brought?  There are a few possible ways you could answer this...