Re: inlaws choosing wedding dress 
Who said the traditions can’t change? I’m just saying that your portrayal of why they are doing it is incorrect and immature.
As for why the tradition started, I’m not sure. My Karachi-based family has roots in Lucknow and Delhi. In both places, the bridal and valima joras come as part of the barri. It’s something I have seen is all of our family weddings, those of my aunts and uncles and those of my cousins as well. It is only the most recent weddings, in the last few years, where some of the brides have insisted on getting the jora themselves, and so they have. Most of the time that’s not what happens. In all cases the MIL has asked the bride what she wants. In some cases, the MIL has picked something in line very close to what the bride wants, in some cases it has been close in MIL’s eyes, but not in the bride’s, in some cases the MIL didn’t know much about what the bride wanted and ended up picking what she thought was best. In ALL cases, the selection has been out of love and a desire to give the bride something that is beautiful and suitable for her, and something that reflects how she feels her bahu should be received.