Just through numerous instructors I have spoken to on the subject. Ip Chun, Kevin Chan, Alan Orr, James Sinclair etc have all said previously that wing chun is not a grappling art. Certainly you can get out of a clinch using wing chun, but you should not be proactively looking to enter a grapple with an opponent.It's mostly a matter of modification. One of the fun parts of Wing Chun is they not only allow, but encourage adapting the style for the one doing it. Judo is also one of the main roots of BJJ, so they shouldn't be too dissimilar. Also, the Judo clinch can be modified slightly by putting one foot forward. You are know basicly in Man Sao Wu Sao.
And how do you know that some of the techniques aren't intended as grappling moves? There are some techniques that I cann't see being even remotely effective as strikely/blocking techniques, but are devestating as grappling moves.
It is like fighting a BJJ guy keeping your feet - he shouldn't then be relying on BJJ to close you down. If you watch the modern UFC guys they won't try the same trick again and agin. If something doesn't work, switch to something else (or another art). If you are fighting a boxer and he is outboxing you, don't box him!!!!
The gym that I train at - Budokwai in london is full of extremely good Judo men and women and they actually suggested using BJJ rather than Judo.
If I am perfectly honest I was loking at many other grappling arts because my Sifu Kevin Chan does BJJ and I didn't want to copy him.
But after looking around I found that BJJ was the best option as a realistic merge with wing chun. I think a lot of people hesitate around BJJ because of the whole claim that BJJ is the best etc. But to be honest I think it certainly is one of the best