Why using timestamp based RTTM simplifies TCP sender?

[Heinz Knocke]

Hi everybody!

While reading quite old but important RFC 1323 in chapter on RTT measurement based on timestamps I found an opinion that: 

" A solution to these problems (rough RTT estimation) which actually simplifies the sender  substantially, is as follows: using TCP options, the sender places a timestamp in each data segment, and the receiver reflects these    timestamps back in ACK segments ..."

and
"Furthermore, the option is probably useful for all TCP's, since it simplifies the sender"

I really coldn't find many arguments, why adding another option will simplify sender's code. I think that no matter what it does, it cannot simplify because the stack needs to be backward compatible, so all previous solutions must stay. Maybe Van Jacobson thought about the situation when timestamp option becomes compulsory, making removal of some old bytes possible? 

Could any of you guys  who are deep into TCP stack code could give me some hints? 

Thanks in advance!
H.K