Yichus gives you a feeling as being part of the elite; like when you attend her family simchas and you are represented as being part of their elite club.
Also usually ‘protektzia’ comes together with yichus. This can help with getting yourself a good job or getting your children into the mosdos of your choice.
Additionally, yichus can give you immediate public recognition, since people will naturally assume that you must be something special if a yichusdik family took you for a son in law.
There is obviously a reason why the Mishna mentions as one of three primary things when searching for a girl, “Tinu Einichem B’Mishpacha”.