The latest episodes have had romulans in them.
And for the record, I am not saying anything bad about Enterprise. I like the show. I simply feel, as do 90% of the fan base, that they should NEVER have use Romulans in the way that they did. Watch TOS "Balance Of Terror" and you will see why. Arguements about Romulans being included are nullified by that TOS episode. It should have been the basis for the series bible when dealing with the Romulans. Sure the Romulans could have been in the series, but not in the way that Brandon and company have used them. That is simply to much of a standing insult to the fan base and they made it clear that they are not happy. Four years and the series is toast.
FAN
"Why did you cancel Enterprise?"
UPN
"Enterprise simply did not meet the needs of our targetted demographic viewer base."
FAN
"What exactly does that mean?"
UPN
"After many days of targeted selection, we came to the conclusion that Enterprise was simply not deverse enough in its execution to meet the educational abilities of our targetted demographic audiance."
FAN
"Excuse me, I don't understand. What exactly does that mean?"
UPN
"Enterprise simply was to cerebral for our viewers."
FAN
"Then you consider your viewers to be stupid?"
UPN
"Exactly. Just look at our programing and you'll see why."