The big changes happened after Rutherfords failed prophecies or big changes that would or could result in many leaving. So first reason is power and control and damage control. After 75% left over rutherfords 1925 prediction and elders in the independent congregations giving their own talks and talking exposing rutherford, he changed to get control of all elders and congregations so troublemakers could be expelled, they had to be approved and reported by the company men, etc.
Holidays and other things to isolate people so they become reliant on the system and less likely to leave or risk loosing their entire social and family status and connections. Holidays and celebrations to show a difference as well and a distinction between JW's and the 'other so called false christians'.
Blood changes for control but slowly things allowed most likely due to GB and high rankers needing or their families needing things so when it effected them, then it was okay.
DFing and apostacy because of the accumalation of false prophecies and false teachings so must tighten control before it gets uncontrollable.
No money for other charities or holidays, etc, as well because having them not get higher education to keep them in the system also results in followers barely having enough money to get by, they want that extra money, so no holidays and no charity, no vacations, make sure that extra money goes to the WT.
No fun, education, anything that may wake somebody up or take from the money and time they have for the WT.