For the most part men wore smocks or something very practical for rural work. The household budget of the average medieval house was mainly taken up with rent to the landlord and/or master of the land you worked. The other half was on food to supplement what you grew yourself. Therefore, there wasn’t a lot, if any, disposable income for clothes. Much of it was made by the lady of the house with her spinning wheel. Wool was the only material available which was great in the winter but unpleasant in the summertime. Apart from dyes made from berries and certain leaves there was little colour choice. Compared to the choice of Farah Shirts from https://www.ejmenswear.com/men/farah it’s quite a remarkable change.
That’s not to say that there wasn’t colour and style. If you were rich enough then you could count on a bit more diversity. You still have to have it in wool.
To get colour you needed to have access to certain plants and flowers and it took a long time for the wool to absorb the colour. For example, Yellow needed reed and tansy plants. Woad was still used for blue (along with a goodly part of urine). Walnuts and oak bark could cover the colour brown.