Lol at the watch... seems it's in place of your dowry!
Engagement presents, later rings were a way of a man showing to your family that he was financially worthy (and capable, by familiarity) of dealing with any assets they might be pasisng to him.
It was always reasonably expensive an item because it would have been dwarfed by the amount of money he would have seen in return in relation to your dowry.
The 'wedding' ring was plain because it was, originally, only a 'keeper' ring for the engagement ring meant to keep that from being lost.
This was back when the engagement was the important, legally binding celebrated in church bit and the wedding less important.
The 'eternity' ring was a manisfestation of the 'x amount of money to be given back to the wife on her production of the heir' clause in a lot of upper class marriage contracts. It was present from husband to wife for completing her role in his affairs to satisfaction, a show of wealth and a sign
that the marriage would be permanent and that the wife wouldn't be 'put away' for not providing as once was something of a tradition.
They've all three morphed into something else entirely now (as has the whole last name change thing....) but, intrinsically, if it was okay for your husband to spend ££ on your ring, why shouldn't he receive something of equal value in return. The modern, equal woman should have no issue with that, surely?
As it happens, I bought my DH an engagement ring, too, and it was more expensive, as, usually, his wedding ring will be, being bigger and wider.