Pros and Cons of extending the term of 7th Pay Commission

Recently the central government announced the extension of term of 7th pay commission by four months till 31st December 2015. By the time there were news started coming about seventh Pay Commission that it would ask one month extension to submit the report, Unexpectedly the central government itself granted four month extension to 7th central pay commission in its Cabinet Meeting held on 26th August 2015
One day before the announcement made by central government on granting extension to the pay commission, according to PTI news report, Justice A.K.Mathur, Chairman, 7th Pay Commission, said that by the end of September 2015 the Pay commission report would be submitted to the government.
Why the central government granted four month extension when the commission itself if asked one month time?
What will happen if the 7th pay commission submits its reports on 31st December 2015?

Before to answer that, It will be very useful to know that what happened in sixth pay commission, after submission of report and how much time it took to get announced the implementation of pay commission recommendation.
The Sixth Central Pay commission was set up by Union Cabinet of India on 5th October 2006. The Commission, headed by Justice B.N.Srikrishna.The Other members of the commission were Prof. Ravindra Dholakia, Mr. J.S.Mathur and Member-Secretary Ms Sushama Nath, IAS.
The Pay Commission submitted its report to Finance Minister P. Chidambaram on 24 March 2008.
The United Progressive Alliance (UPA) Government headed by Manmohan Singh, approved the Sixth Pay commission recommendations with some modifications. In the cabinet meeting held on 14th August 2008, the Union Cabinet headed by Manmohan Singh gave its approval for implementation of the recommendations of the Sixth Central Pay Commission.
It was announced that the revised pay scales will come into effect from 1/1/2006 and revised rates of allowances from 1/9/2008.
The Gazette Notification for implementation of sixth pay commission published on 29th August, 2008.
From the above reference it is known that after submission of report it will take six month time to get its approval from Central Government for implementation of pay commission recommendation.
The decision of extending the term of seventh pay commission could be a major blow to central government employees by the way as follows
1. The 7th pay commission has been made to submit its report on 31st December 2015. The stipulated time is extended as 22 Months instead of 18 months for 7th pay commission to submit its report
2. As the central government would like to ground upon the Precedents and it will take six month time from the date of submission of report to announce its approval for implementation of 7th pay commission recommendations
3. So the Cabinet approval for implementation of 7th pay commission recommendation will be granted by the Month of June 2016
4. Only the Revised Pay Scale will come into effect from 1.1.2016
5. The revised rate of allowances will come into effect from prospective date that is with effect from the day of Order is issued.
6. So the central Government employees will be losing the benefit of revised rate of allowances for the period of six months , which they supposed to get from 1.1.2016, provided the order for implementation of 7th pay commission will be issued on 1.7.2016.