Don't replace those struts unless they are leaking or not working. I just replaced mine since everyone told me I needed to replace them, because my car was 23 years old and had 250,000 miles on it. After replacing them my ride felt like I was running on solid rubber tires. I could feel every rock and pebble I ran over. I am now going to remove the new Monroe struts and reinstall my old struts to get back my smooth soft ride. My old struts were not leaking but did not have any gas charge left in them when I removed them. I have spent a lot of money and done a lot of work for nothing. Now I have to start all over and put the old ones back on. The only good thing is I now know how to change them.
So if you are not bouncing around and bottoming out when you are driving around, leave them alone and save yourself some money and time. Now if you like a stiff hard ride change them.

 

Two thoughts:
1.) Did you buy exact replacements for your trim level or is it possible you got ones for a sporty version of your vehicle (or even an aftermarket one geared towards an even more sporty ride)? This wouldnt explain the ride being that harsh, but it would explain it feeling much tighter than a 23 year old one.

2.) If it truly was like driving on solid tires / you feel every rock in the road, that sounds a lot more like a manufacturing defect - perhaps one or more had the transfer holes that were either not fully drilled out or not drilled at all. This sounds like the whole thing is solid locked up / carrying all of the load for it to ride that hard. Ive had some very sporty shocks on vehicles (even with very thin sidewall tired) and it's never been anywhere near what you're describing for an oem replacement type unit.