Yes, investigations should continue into whether Russia interfered into the election. Interference in election by foreign powers is a very serious issue. If this indeed happened, punitive measures must be taken to ensure that other foreign powers are discouraged from interfering in future elections. Without punishment, it can easily happen again.
The investigation in an important part to reach an understanding of the true intentions of the Russian intelligence, on why they interfered onto the American election of November 2016, by leaking thousands of emails of the Democratic candidate. The fact that the leaks were one sided raises many question on what their real intentions were, which side they are supporting and why.
The question of whether Russia interfered in the US election is one that needs to be answered. It is vital that US elections maintain their legitimacy and the confidence of the governed. If Russia did interfere, the extent and method of the interference should be determined. Once the method is determined, solutions should be sought to avoid such interference in future elections.
Back when people thought that Clinton was going to win the election, the media was running reports telling people that Russia was not interfering in the election. The people were told that the results of the election were fair and that the people should abide by them. Now that Trump has won, the same people are crying interference.