They would take absolutely anything if they could, not just a GTi. The copper who attended our 'break in' said that he has also attended properties which had a (to include) Honda Jazz and Suzuki Swift stolen. You'd expect that these may have been opportunist but no, they broke in at night to steal the keys for these cars too.
(i) If you have a house alarm than they only have time to rumage downstairs before the alarm goes off fully. They probably wouldn't have time to go upstairs and confront the householders.
(ii) Also, many banged-up/reformed burglars have admitted to avoiding residential properties with CCTV; (a) for the obvious reason) and (b) they do not know if the property has internal (possibly pinhole) cameras and/or security bugs inside the house.
(iii) They also think that if one property has CCTV, then others in the area will do too. Thus, meaning other CCTV systems may catch images of their transportation prior to arriving to their targetted property etc, or any other footage prior or after the crime
Hope this helps
Red