Its still the same reason bungie didnt want people getting god rolls right away

Well they both had their pros and cons. Also back then getting materials was not as easy as now, Specially motes of light, I remember when reforging started having thousands of them and running out of motes within a few days after constant rerolling. Reforging had the con of you needing to get the weapon first, which sometimes could be an issue since weapons were not always easy to get, matador64 etc were not weapons that would drop that often in crucible so you would need to farm for that first. The pros is that once you had the weapon all you have to do is reforge until you got them, but I remember running out of materials very quickly, and I am not sure if planetary materials were easily to obtain back then, plus, your shards were capped at 200. The menagerie mades is simpler, since if you want the weapon all you need to do is set the specific run and thats it, however, getting the correct rolls is much harder than with reforging. If I have to choose I would say reforging was more broken than the chest exploit. Simply because once you had the weapon you could just reforge until you get what you wanted. This was probably an issue mainly on PVP, thats why they stopped it. Plus once you get the roll you want on a weapon whats the point in reforging again? So bungie fear that people would stop playing their game once they got all the gear they wanted.