Several leagues do this, as you would know, what would play for.
In Germany, Spain, France, Netherlands, it´s the last two league matches that all start at the same time and date.
In England and Italy, it´s just the last one. Obviously, there are many occasions when the league is already decided.
What that means? Well, in Italy, Roma is 3rd, Napoli is 2nd. Roma plays tomorrow and are finished before Napoli starts. Let´s say Roma lose (unlikely, but possible) and Napoli draws. Napoli would get ahead by 3 points and the direct CL spot is almost garanteed (better goal +/-) with 3 more points and one match to play. Napoli could settle for the draw in the last minute, instead of running for the 3 points and possibly losing.
If they are playing at the same time, such scenarios are much harder to think through with guys sitting on radios/TVs and checking what happens in other stadiums. Of course, it will happen also, but i guess it just affects your play on the last day of the season.
In Germany, you basically know Bayern will most definitely will be champion, Dortmund 2nd and Leverkusen in 3rd, which is kind of boring. But the rest if up for grabs, you don´t know 4-7 (one CL, 3 Europa League spots), who will get relegated with Hannover, who will play relegation matches (up to Augsburg in 12th position, so it´s basically 6 teams fighting for survival), so if you had them playing one after another, it would be boring and everybody knew what would be enough and you had teams settling for results.