I've always been wary of the concept of a "sexual peak" for men and women, and certainly skeptical to the idea that such a sexual peak can be generalized in any meaningful way. Everyone has a different body and a different lifetime of experiences affecting the body and the mind. Therefore everyone will find different point in their lives where their libido's are higher or lower (and sexual peak may not simply refer to libido). It is true that sex hormones generally slow in production with age, especially in the US where chronic stress tends to reduce sex hormone production but a "sexual peak" for many people is probably not measured simply by the presence of sex hormones but by other physical and mental factors.
As for menopause you will find significant hormone disruptions in many women in the US (and probably elsewhere but my studies are largely US focused). My beliefs at this time are that such disruptions are the result of various dysfunctions present in the body. One theory I've been studying is that menopause is the time when estrogen production ramps down in the ovaries and ramps up in the adrenals but since the adrenals of so many women are completely shot this leads to a significant disruption of the endocrine system which is the root of many or most of the typical symptoms associated with menopause. Again, this is not going to be true for every woman but it seems like a prevalent pattern in the US.
This falls in line with my research as well. The body needs to be considered as whole and not fragmented. The interaction/dependency of one organ to the other is like a delicate symphony and if one instrument is out of tune there will inevitably be discordancy.
There is a also a basic maintenance of the vaginal muscles and cultivation of sexual energy that can play a big role in keeping the area healthy and vibrant. Just as exercise does for the body in terms of flexibility, strength, energy and overall health. The Indians and Taoists didn't devote so much time towards the sexual arts for nothing. Reaching higher levels of pleasure was not the one sole purpose.
It may be tempting to utilize sythetic hormones to make up for the imbalance however one is still just working symptomatically. Then because these hormones are coming from a source external to the body's natural intelligence/agenda and via the medium of tissues that are not meant for this purpose to begin with, this ends up creating confusion in the body, most especially as to how to utilize/metabolize them properly. From there come all of the "unwanted secondary effects".