Shirib if you think that the simple arguments that you put up have any weight, then long ago people would have stopped doing it (if you can accept that there were many many many great ulema before you, who have dealt with this issue). This is a tradition that has lasted over a thousand years, and the greatest of our ulema have for the most part agreed with it. And they have come up with a simple very easy guideline: first you must know it is not an obligation (fard) to do it, two it is not a sunnah of the rasul or sahaba in the way it is done now, three if you are against it because you fear going out of the boundaries of the Sunnah then there is nothing wrong with that and you will not be questioned as to why you didn't, three if you do it with in the boundaries of the shariah of what is permissible then it is a meritorious thing with many rewards and benefits for those who do it.
The benefits of it are many, and here are a few. It gives a chance for believing brothers and believing sisters to come together, and any gathering that comes together for noble reasons is loved by Allah, and the angels descend on the gathering to pray for the believers and Allah forgives all those who intend, and some even say even those who did not come for the same intent and just were present without taking part in it will also be forgiven by Allah because of his Rahma. The Qura'an is recited, and you very well know the benefits of the Qur'an and it is multiplied exponentially within gatherings because of how much Allah loves gatherings for his sake and his beloved (saws). The seerah of the Rasul(saws) and his sahabah is recounted and once again remembered in the hearts of the believers and their love for him increases in their remembrance. Then they send Salawat (prayers) Salaams (salutations) on the rasul(saws) which is an obligation on every muslim and it can never be done to much of, and they ask to be among those who the Rasul (saws) intercedes on behalf of when there is no greater intercession than that of the Rasul(saws) (may allah make us among those who receive this because of our love of the Rasul (saws) ). Some of the benefits of sending salawat and salams on the Rasul (saws) are that they are forgiven 10 bad deeds and earn 10 good deeds, Allah raises their degree by 10, and for everytime you send salwat allah sends 10 on you.
These are just some basic reasons, and if you see it as it is, it is hard to disagree with. You can be among those who accept it as something that will never go away and has lasted better part of the history of islam, if you choose to not do it because you believe it is not part of the sunnah may Allah reward you for your noble intentions, or you can be among those who attack, deride, mock, and insult those who don't agree with you.
edit: Also bringing food is a sunnah for gatherings and you recieve ajar iyo xasanah for it, so again that is a good thing.
If you can't attack these things individually, to me they seem like ingredients that make an excellent recipe when added together.
Also this is done on other important dates that commensurates something great like Mi'raj (when the Rasul(saws) got to a point near to Allah that no creation has ever gotten to.




