I suspect that the reticence proceeds from several factors. First, it takes a long time to construct your own Synopsis, even of just the one pericope. Many scholars are computer-literacy-challenged and balk at the pain of constructing their own Synopsis, with all its word alignments and line breaks, let alone having to master the use of a decent Greek font.
Moreover, some scholars have never taken a course on the Synoptic Problem and are reticent to risk exposing their ignorance by constructing a Synopsis that misses key pieces of data.
And many scholars are happy with the existing Synopses on their desks (these days usually Aland, though some, like me, still prefer Greeven) and they assume, wrongly, that their readers will turn up the relevant page in the Synopsis when they are reading the article.
But there are so many benefits to producing your own illustrative Synopses of Gospel passages in your academic writing. For one thing, there will often be a specific piece of data to which you wish to draw attention. Producing your own Synopsis, perhaps with some nice underlining to draw attention to the key point, can help the reader to visualize the data instantly, and without the added hassle of looking up the passage in Aland or Greeven.
The effort involved is nothing like as bad as it was in the days of typewriters and drawing. Although it can sometimes be a little frustrating, producing Synopses is like any other element in word-processing -- practice makes perfect. A simple table is the way to do begin, with single line spacing, no paragraph spacing or indents, left alignment and lots of carriage returns. There are plenty of good electronic texts that you can use as the base text too, even if one wishes to tweak them.
Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it, 'and what is the use of a book,' thought Alice 'without pictures or conversation?'As Alice knew, pictures and conversation break up bland and boring blocks of text. Far too many articles on the Synoptic Gospels are made up of boring old blocks of prose, with no Synopses or tables. And what is the use of an article, thought Mark, without Synopses or tables?