You might not need to roll over your 401(k) into an IRA, but it might make sense

Investment companies and professionals are going to try and make it seem that rolling over your 401(k) into an IRA is urgent. This mostly has to do with the fees they earn by getting you to switch. They are incentivized to get you to think it is urgent.
I care about what is right for you, and you should too! You can always rollover at a future time. If your balance is more than $5,000, you a legally entitled to keep your 401(k) where it was at your old job. When you have $5,000 or less, your former employer can involuntarily remove you for their 401(k) plan without your permission.
Here is the important part: Most 401(k) plans offer few investment options, maybe two or three dozen at most, most will be mutual funds. If you roll that 401(k) into an IRA, there will be thousands of choices including more than just mutual funds like ETFs, individual stocks and bonds, and certificates of deposit. I like passive index ETFs like the S&P 500.
Works Cited:
http://www.401khelpcenter.com/401k_education/involuntary_distribution.html#.ZFFeg87MKUl
https://www.wsj.com/buyside/personal-finance/401k-rollover-af1e517?mod=wsj_hp_buyside_pos1