Yes, it sounds like they are being unusually opinionated. It’s not their job to decide the wedding details, it’s their job to support you. I really don’t agree with nikipedia at all. I don’t think you’re being unreasonable…
Your bridesmaids might be asking to come to events and check out vendors with you because that’s their way of trying to be supportive. If it’s not helpful to you, you should thank them profusely and explain that it’s easier for you and your fiancee to make these decisions just the two of you.
Weddings can be a fine line to walk, between a community event and an event for a couple…just stay patient, take some deep breaths, and remind yourself that it’s a blessing to have friends who want to be so deeply involved in your joyous occaision (and then find a respectable and polite way to encourage your bridesmaids to back off).
The one exception to this would be if you are asking them to spend a tremendous amount of money on a dress and shoes, it does make sense if they want to weigh in a little on the dress—and it’s polite of you to ask/include them in that. One of the best ways to do it is pick a color/fabric with some different patterns so that each can pick the cut that looks best for her. It’s really hard to find a dress that looks good on every woman’s body, and it’s really tough for the bridesmaids to have to pay $300 for a dress that they think is unflattering and they will never wear again. Then again, that is part of the shtick of being a bridesmaid…
You can also tell them that you want them to focus their energies on planning the best-ever bachelorette event. That gives them a way to feel useful and also gets them off your back for the other stuff you want to do on your own.