The pitch doesn't offer any support to the bowlers and even if they extend the duration to 10 days instead of 5 days, it will still end up as a draw. These matches are a reason why test format is dying. You waste 5 days consecutively to watch them playing and the match still end with no result.
If you looks at the matches in the past 6 to 8 years we have results in Test matches most of the time and the matches that ended up in a draw was really competitive where the team was fighting to defend from the brink of a defeat, so things have changed and rarely we see matches like this that are played in dead pitches that do not help the bowlers and hopefully the ICC gives out warning to make pitches better the next time around.
I am not saying that most of the test matches are like this one. But this series has been disappointing so far. Let's not forget the fact that these two teams rank among the bottom half of the World Test Championship. So in order to improve their ranking, they needed a few wins. I am especially disappointed with Sri Lanka, who are the hosts. If they are so defensive against a team such as Bangladesh, then how they can compete against the big three teams?